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had passed three hours before. The Waboni tribe, who live Around the disk is a black ring quarter inch broad: some , hunting, and use the bow and arrow, occupied the thick times the milling of the coin causes radial lines across this halo. oods of the lower river. Above them the curves became more 1 If carefully protected there appears to be no limit to the perntle, and the Gusha district was reached, where the people manence of ihe figures, but commonly they are gradually utivaled the land, which was cleared by burning ; and for a obscured by the dust gathered up after being often breathed indred miles the Kenia's furnaces were fired with the dead upon : some of the early ones, done more than two years back, ees which had been killed, but lelt unburnt by the fire. Cotton | are still clear and well defined in the detail.
cultivated as well as food plants, and there is a primitive It is possible to efface them with some difficulty by rubbing stem of weaving. Above Bilo, and about 100 miles from the with a leather whilst the glass is moist. They are best preserved a, a branch was found to run off from the main river to the by laying several together when dry and wrapping them in uth-west through very dense forests. This is probably the paper : they are not blurred by this contact. heri, which reaches the sea midway between Lamu and Kis It is a curious fact that certain developments take place after ayu ; the land between this and the Juba mouth being pro. a lapse of some weeks or months. The dark ring around the bly of deltaic origin. This branch was explored in a boat for disk gradually changes into a series of three or four, black and lenty miles. The dense forests formed a broad belt on both white alternately ; other instances of such a change will be noted les on the river, and alter steaming for five days through un. below. habited woods the Kenia suddenly emerged into open country Let it be noticed that in coin pictures the object is near to, | August 2. The people were of very mixed race, friendly and but not in contact with, the glass : for in the best specimens the ell supplied with all sorts of food. Hills began to appear, and rim of the coin keeps the inner part clear of the surface. e river grew shallower, until on August 1o the steamer moored Obviously a small condenser is made by the coins: it is not the bank opposite Bardera. Here the Sultan forbad a land essential ; at the same time images made by a single coin, put to g, and the people, who numbered about 1200, were hostile, a single pole, are inferior. it ultimately peace was arranged, and one of the subordinate The plan which gives the surest and most beautiful results is leiks accompanied the Kenia to the rapid., where the river to place five or six coins, lying in contact side by side in a cross veeps between sleep rocky hills 30° to 400 feet high. There or star, on either side of the glass : it is not necessary that each e three channels in the rapids, but at the time of the visit none coin should exactly face one on the other side. as navigable, and the natives reported a waterfall over a ledge There has not appeared any distinction between the figures
rock about four hours' march further up, in latitude 2° 34' N. | made by positive and negative electricity. he wreck of the Guelph was visited and examined, but the When several coins are placed side by side, touching one another, pid falling of the water made it necessary to hasten back to there appear in the spaces between them, which are mostly e sea. The climate throughout was found agreeable, and black, well-defined white lines, common tangents to the circular ere were few mosquitoes. The river does not overflow, so edges of the coins. If these are of equal size the lines are straight ; ere are no malarial swamps along the banks.
otherwise they are curved, concave towards a smaller coin.
They seem to be traces in that plane of the loci of intersecti on -- -- -
of equipotential surfaces.
Similar effects are obtained when coins a nd glasses are piled BREATH FIGURES.
up alternately, and the outer coins are put to the poles of the
machine. With six glasses and seven coins perfect images have 'IFTY years back Prof. Karsten, of Berlin, placed a coin
been formed on both sides of each glass. With eight glas es the upon glass, and by electrifying it made a latent impression,
figures were imperfect ; but there is little doubt this could be ich revealed itself when breathed upon. About the same time
improved by continued trials as to the amount of electricity :: W. R. (now Sir W. R.) Grove made similar impressions
applied. h simple paper devices, and fixed them so as to be always
If several glasses are superposed and coins are applied to the ible. A discussion of Karsten's results occurs in several places,
outer surfaces, there are only the two images at the outside. ! I have not been able to find details of his method of per
After the electrification there is a strong cohesion between the ming the experiment. During my attempts to repeat it some
plates. cts have appeared which seem to be new and worthy of
It requires some practice to manage the electrification so as to ord.
produce the best results. There are two forms of failure which After many trials I found the following method the most
present interesting features. Sometimes a picture comes out cessful :-A glass plate, six inches square, is put on the table
with the outlines dotted instead of being continuous. At other insulation : in the middle lies a coin with a strip of tinfoil
times, if the electrification is carried too far, the impression comes ng from it to the edge of the glass : on this coin lies the glass
out wholly black; but on rubbing the glass when dry with a be impressed, four or five inches square, and above it a second
leather the excess is somehow removed. Naturally it is difficult a. It is essential to polish the glass scrupulously clean and
to rub down exactly to the right point, but I have succeeded on with a leather : the coins may be used just as they usually several occasions in developing from a blank all the fine detail or chemically cleansed, it makes no difference. The tinfoil lof elaborate coins. the upper coin are connected to the poles of a Wimshurst
Here, again, we have another instance of the development by hine which gives three or four inch sparks. The handle is
| lapse of lime, for an over-excited piece of glass usually gives a ed for two minutes, during which one-inch sparks must be
. clear picture after an interval of a day or two. passing at the poles of the machine. On taking up the
| Impressions from stereotype plates have been taken of which one can detect no change with the eye or the microscope ; , the greater part is legible: the distinctness usually improves when either side is breathed upon, a clear frosted picture
after a few days. In default of a second plate, a piece of tin-foil ars of that side of the coin which had faced it : even a
about the same size should be put on the opposite side of the tor's mark beneath the head may be read. For convenience
glass. parts where the breath seems to adhere will be called white,
Sheet and plate glass of various thicknesses have been used ther parts black. In this experiment the more project ing
without any noticeable change either in the treatment or the of the coin have a black counterpart, but there is a fine
results. ation of shade to correspond with the depth of cutting in the
I have put an impressed glass on a photo 'raphic plate in the e: the soft undulations of the head and neck are delicately
dark, but did not get any result on developing : my impersect duced.
skill in photographic matters leaves this experiment inconclusive. le microscope shows that moisture is really deposited over
Probably all polished surfaces may be similarly affected : a bole surface, the size of the minute water granulation
plate of quarız gives the most persect images, which retain their using as the point of the picture is darker in shade.
freshness longer than those on glass. ere seems to be no change produced by the use of coins of
Mica and gelatine give poorer results : it is not possible to ent metals.
polish the surlace to the necessary point without scratching it. parking is allowed across the glass instead of at the poles
On metal surlaces fairly good impressions can be produced if, 'machine, traces of metal are sometimes deposited beyond
as Karsten advises, oiled paper is put between the coin and the ak of the coin, but not within it.
surface. per read by Mr. W. B. Croft before the Physical Society of London on
In the order of original discovery the figures noticed by Peter 6. 2892.
| Riess should come first. He discusses a breath-track made on
glass by a feeble electrical discharge ; as well as two permanent Some writing is made on paper with ordinary ink and di marks, noticed by Ettrick, which betray a disintegration of the | dried : it will leave a very lasting white breath-image after a las surface.
hours' contact. If, with an ivory point, the writing is trace I have found that when a stronger discharge is employed more with slight pressure on glass, a black breath-image is made : complex phenomena of a similar kind are produced." A six-inch once. Of course this reads directly, and the white one iovann Wimshurst machine is arranged with extra condensers, as if to It is convenient to look through the glass from the other on pierce a piece of glass. If this is about four inches square the for inverse impressions, so as to make them read direct. spark will generally go round it. For a day, more or less, there Plates of glass lie for a few hours on a table-cover wurm is only a bleared watery track, i inch wide, when the glass is with sunflowers in silk : they acquire strong white figures is breathed upon ; but after this time others develop themselves the silk. within the first, a fine central black lire with two white and two 1 In most cases I have warmed the glass, primarily for the sun black on either side, the total breadth being the original i inch. of cleansing it from moisture; but I have often gone to a la These breath-lines do not precisely coincide in position with the beyond what this needs, and think that the sensitivedes be permanent scars, but the central one is almost the same as a been increased thereby. permanent mark, which the microscope shows to be the surface. It is not easy to imagine what leads to the distinction betres of glass fractured into small squares of considerable regularity: black and white, different substances act variously in this resea on either side is a grey-blue line always visible, which Riess I have placed various threads for a few hours under a pies : ascribes to the separation of the potash. After several months glass, which lay on them with light pressure : wool gives bisa I found two blue lines on either side, which I believe were not silk wbite, cotton black, copper white. A twist of tinse 2 visible at first. Of course these blue lines may be seen on most wool gives a line dotted white and black ; after a time ting Leyden jars, where they have discharged themselves across the traces show signs of developing into multiple lines as c glass.
spark figures. In 1842 Möser, of Königsberg, produced figures on polished | Two cases have been reported to nie where blinds Free surfaces by placing bodies with unequal surfaces near to them ; bossed letters have left a latent image on the window near the action was ascribed to the power of light, and his results were they lay ; it was revealed in misty weather, and had do compared with those of Daguerre. Möser says, “We cannot removed by washing. I have not had a chance to see thet therefore doubt that light acts uniformly on all bodies, and that, myself, but both my informants were accustomed to sca moreover, all bodies will depict themselves on others, and it observation. only depends on extraneous circumstances whether or not the | A glass which has lain above a picture for some years, the. images become visible.” In general, the multitude of images kept from contact by the mount, will often show on its would make confusion ; it can only be freshly polished surfaces side an outline of the picture, always visible without brez that are free to reveal single definite impressions. However seems to be a dust figure easily removed : possibly heat and great Möser's assumption may be, there are many achievements have loosened fine paint particles, and these have been drar: of modern photography that would be as surprising if they were | to the glass by the electricity made in rubbing the outer siz: not so familiar. I have not the means of knowing the precise clean it. The picture must have been well framed and a form of Möser's methods : in the experiments which follow there from external infuences; most commonly dust and dampf is usually contact and light pressure, and if they are not wholly | and obscure such a delicate effect. analogous, they may for that cause help to generalize the idea : I am not able to suggest simple causes for these varied er in none of these is electricity applied.
I am not inclined to think, except in the case of water-cas A piece of mica is freshly split, and a coin lightly pressed for which is hardly part of the enquiry, that there is a det thirty seconds on the new surface : a breath-image-of the coin material deposit or chemical change ; one cannot suppe is left behind. At ihe sanie time it may be noticed tliat the | imperceptible traces of grease, ineradicable as they want breath causes abundant iridescence over the surface, whilst it is would produce complete and delicate outlines. The ders! in a fresh state. It is not clear how the electricity of cleavage off of impressions may at first seem to indicale a deposit ; * can have an active agency in the result.
this renewal of the surface might rather be like smoothing It is familiar to most people that a coin resting for a while on an indented tin-foil surface : such a view might explain the st glass will give an outline of the disk, and sometimes saint traces where a blank over-electrified disk is developed into fue $ of the inner detail when breathed upon.
The electrified figures seem to point to a bombardment, vt An examination-paper, printed on one side, is put between produces a molecular change, the intensity of electricity be two plates of glass and lelt for ten hours, either in the dark or about quickly what may also be done by slow persistent E the daylight : a small weight will keep the paper in continuous of mechanical pressure. At present it seems as if nose contact, but this is not necessary if thick glass is used. A perfect phenomena cannot be drawn out from the unknown to breath-impression of the print is made, not only on the glass molecular agency. which lay agairst the print, but also on that which faced the While experimenting I was not within reach of relereis blank side of the paper. Of course the latter reads directly, former researches, but I have since done my best to fod and the former inversely; the print was about one year old, and out, and to indicate all I have learnt in the body of me presumably dry.
Poggendorff, vol. Ivii. p. 492 ; translated in Arile More often both impressions are white, sometimes one or other l'Electricité, 1842, p. 647. or both are black. At other times the same one may be part Riess' “ Electrische Hauchfiguren” in “ Repertorius white and part black, and they even change while being
Physik”; translated in Archives de r Electric examined.
p. 591. During a sharp frost with east winds early in March, 1890, Reiss Die Lehre von der Reibungs Electricitat," va these impressions of all kinds were easy to produce, so as to be
Taylor's “ Scientific Memoirs," vol. iii.
Dulong and Petit, by Rosetti, Stefan, and Weber, were The following experiments easily succeed at any time :- Stars for a comparatively small range of differences by a de and crosses of paper are placed for a few hours beneath a platetion of the heat radiated from an iron disc at a disa of glass : clear white breath-figures of the device will appear. about 30 cm. from a thermopile. The results tende A piece of paper is folded several times each way to form small that H. F. Weber's formula (Sitzungsber., Berlin, 18 squares, then spread out and placed under glass : the raised lines | most closely with experiment. Stelan's formula, 2013 of the folds produce white breath-traces, and a letter weight which the heat emitted in unit of time is proportional that was above leaves a latent mark of its circular rim.
fourth power of the absolute temperature, is also fairly
Dulong and Petit's values are too high, and Rosetti's too near Elgin, which are now in the possession of the Elgin 1.-Notes on silver, by M. Carey Lea.-Notes on silver Museum and of the Geological Survey. These specimens repreorides, by the same. Fused silver chloride poured into sent at least eight distinct skeletons, seven of which undoubtedly roleum and placed in the sunlight without removing it from belong to the Dicynodontia, and one is a singular horned reptile,
liquid, is instantly darkened. From this it appears that the new to science, All the remains yet found in this quarry are in sence of oxygen or moisture is not essential to the darkening the condition of hollow moulds, the bones themselves having silver chloride in light. The chlorine may be taken up by entirely disappeared. In order, therefore, to render the specije other substance.-A remarkable fauna at the base of the mens available for study, it was necessary, in the first place, so 'lington Limestone in north-eastern Missouri, by Charles to display and preserve these cavities that casts might be taken lin Keyes.-Glacial pot-holes in California, by H. W.Turner. which would reproduce the form of the original bones. Gutta"he lavas of Mount Ingalls, California, by H. W. Turner. percha was found to be the most suitable material for taking i method for the quantitative separation of barium from stron these impressions ; and in some instances, especially in the case a by the action of amyl alcohol on the bromides, by Philip | of the skulls, the casts had to be made in several parts and afterBrowning. The solubility of barium bromide is about o'0013 wards joined together. . on the oxide in 10 cc. of amyl alcohol, while that of stron1 The first specimen described is named Gordonia Traquairi; 1 bromide is 0'2 grm. To obtain the bromides, the pre- it is the one noticed by Dr. Traquair in 1885, and referred to the lated and thoroughly washed carbonates of Ba and Sr are Dicynodontia ; besides the skull, it includes fragmentary portions ted with hydrobromic acid obtained by the action of dilute of other parts of the skeleton, and is contained in a block of sandhuric acid on potassium bromide. —Note on the method for stone which has been split open so as to divide the skull almost quantitative separation of strontium from calcium by the | vertically and longitudinally. The two halves have been so on of amyl alcohol on the nitrates, by P. E. Browning, developed that casts made from them exhibit the left side and ent work on this method has shown that the total correction upper surlace, as well as the main parts of the palate and lower yunts to O'0006 grm. on the strontium oxide, and o'0010 on jaw. In general appearance this skull resembles those of Dicy. calcium as sulphate. -Study of the formation of the alloys | nodon and Oudenodon. The nasal openings are double and in and iron, with descriptions of some new alloys, by W. P. directed laterally ; the orbits are large and look somewhat foradden.-Notes on the Cambrian rocks of Pennsylvania and wards and upwards. The supra-temporal fossa is large, and ryland from the Susquehanna to the l'otomac, by C. D. | bounded above by the prominent parieto squamosal crest, and Icott. – Volcanic rocks of South Mountain in Pennsylvania below by the wide supra-temporal bar, which extends downwards Maryland, by G. H. Williams.
posteriorly to form the long pedicle for the articulation of the l'iedemann's Annalen der Physik und Chemie, No. 11.-On
lower jaw. There is no lower temporal bar. The maxilla is behaviour of allotropic silver towards the electric current,
directed downwards and forwards to end in a small tusk. Seen A. Oberbeck.-On the indices of refraction of dilute
from above, the skull is narrow in the inter-orbital and nasal tions, by W. Hallwachs.-On capillary constants, by M.
regions, but wide posteriorly across the temporal bars, although tor.-On the chemistry of the accumulator, by M. Cantor.
the brain-case itself is very narrow. There is a large pineal n the fall of potential during discharges, by O. Lehmann.
fossa in the middle of a spindle-shaped area, which area is formed eries of important investigations on discharges between
by a pair of parietals posteriorly and a single intercalary bone frodes and in tubes without electrodes.-Expansion of water
anteriorly. the temperature, by K. Scheel.- A method for determining
The palate is continuous with the base of the skull; the density of saturated vapours and the expansion of liquids at
plerygoids on each side send off a distinct process to the quadrate er temperatures, by B. Galitzine. This method has the
region. Towards the front the mediam part of the united intage of extreme simplicity combined with accuracy.
pterygoids arches upwards, and the outer sides descend, forming
A I glass tube, about 5 cm. long and a few mm. thick, is
a deep groove ; from the evidence of other specimens it is clear ed at one end and drawn out into a capillary at the other.
that the palatines, extending inwards, converted this groove into I determining the weight and internal volume of the tube,
a tube, and thus formed the posterior nares. The ramus of the all quantity of the substance to be investigated is introduced
lower jar is deep, with a large lateral vacuity, and the two rami it in the liquid state. This is made to boil, and then the
are completely united at the symphysis. The back of this skull is sealed by fusing. On raising the temperature, the sur
is not seen, but two other specimens, referable to this same of separation between the liquid and its vapour is
genus, show that the occiput had two post-temporal sossa on laced, until at a certain temperature all the liquid is
This specimen is distinguished from Dicynodon by the preserted into saturated vapour. The tube is then cooled until vapour reappears, when the temperature is again taken.
ence of two post-temporal fossæ on each side of the occiput, by can be repeated several times, thus giving an accurate value
the small size of the maxillary tusk; and probably by the he density of saturated vapour at a certain temperature.
elongated spindle-shaped area enclosing the pineal fossa, and
also by the slight ossification of the vertebral centra. same process can be used to determine the expansion of the d. As the temperature rises, the volume of the liquid will
A second and much smaller specimen, provisionally referred
to G. Traquairi, has, besides the skull, a fore-limb well preneral increase up to a certain point, when the vaporization nes more pronounced. This maximum, which can be ob
served. The humerus of this shows the usual Anomodont d more accurately by drawing out the tube near that point,
expansion of its extremities; its large deltoid crest is angular, a value for the expansion. For the density at that point
and set obliquely to the distal end.
Three other species are referred to the same genus, namely :function of the density at oo C. and the temperature,
Gordonia Huxleyana, which is distinguished from G. Traquairi he pressure is that of the saturated vapour at the same rature. Thus it is only necessary to find the volumes of
by its proportionately wider and more depressed skull, and by
the absence of the concavity between the orbits which is present quid and the vapour, and the density of the latter from the
in the latter species. The humerus has the distal extremity sus experiment.-On radiant energy, by B. Galitzine.on the electricity of waterfalls, by J. Elster and H. Geitel.
oblique to the deltoid crest, which was probably rounded and paratus for demonstrating the Wheatstone bridge arrange.
G. Duffana has the skull even wider than in G. Huxleyana, by A. Oberbeck.-Determination of the coefficient of
and the portion of a humerus found with this skeleton has the duction by means of the electro-dynamometer, by O.
two extremities set nearly at right angles to each other.
G. Juddiana has an elongated skull resembling that of G. Traquairi, but the parietal crests are less developed, the bones
of the pasal region are much thickened and overlap the nasal SOCIETIES AND ACADEMIES.
apertures, the small tusk is placed a little further back and LONDON.
points more directly downwards, and the pineal fossa is
smaller than in either of the other species. 'al Society, December 15.-On some new reptiles from A second generic form is named Geikia Elginesis. This is a gin Sandstone, by E. T. Newton, communicated by Sir | skull nearly allied to Ptychognathus, Owen, but is distinguished ald Geikie, F.R.S.
| by its shorter muzzle and the entire absence of teeth ; the upper ng the last few years a number of reptilian remains have part of the skull, between the orbits, is also peculiar, forming a btained from the Elgin Sandstone at Cuttie's Hillock, deep valley open anteriorly, with a ridge on each side, the anterio
end of which forms a large prominence above and in front of the between crossed polarizer and analyzer, the author went on: orbit. The occiput has only one (the lower) post-temporal sossa say that several books on optics implied that the numbers open on each side. The maxilla is produced into a tooth-like hands in the spectra of these colours was the same as the order prominence, which occupies a similar position to the tusks of of the colour. On obtaining selenites of the first four orders Gordonia ; but the hone is too thin to have supported a tooth, of red from Messrs. Steeg and Reuter, he found that the firs and in all probability it was covered by a horny beak. The three orders gave one dark band each, and that of the foe lower jaw has a strong symphysis, a distinct lateral vacuity, and order three dark bands. Further experiments showed that ta the oral margin, at the foot of each ramus, bears a rugose thicknesses of the selenites were in the proper proportions a prominence.
quired to give the first four orders of red. The numbers i Elginia mirabilis is the name proposed for the skull of a bands, the author explained, depended on the numerical posreptile, which, on account of the extreme development of horns bilities of wave-length within the visible spectrum--ther and spines, reminds one of the living lizards Moloch and Phry whether a multiple of the wave-length of one visible wave at nosoma. The exterior of this skull is covered in by hony plates, he another multiple of a different wave. For example, tai the only apertures being the pair of nostrils, the orhits, and the the visible spectrum as extending from A (0*000760; to F1 pineal fossa. The surfaces of the bones are deeply pitted, as in (0'000394) and the wave-length of the line E in the green a crocodiles and labyrinthodonts. The horns and spines, which o'000527, it was shown that the first order of red was dz vary from } in. to nearly 3 in. in length, are found upon nearly extinction of green by a thickness of crystal proportiona » every bone of the exterior. The development of the epiotics, IX 0'000527, and would give one band in the green. Forte: and the arrangement of the external hones, resemble more the second order, the thickness of crystal was proportiona! Labyrinthodont than the reptilian type of structure ; while the | 2 * 0'000527, viz. O'001054, and this number was no oke palate, on the other hand, conforms more nearly to the Lacer. integral multiple of any other wave-length between A and H tilian type, and, with the exception that the pteryguids are consequenily there could only be one band. Similarly is . united in front of the pterygoid vacuity, agrees with we palate shown that the third order of red could only have one bani of Iguan and Sphenodon. There are four longitudinal ridges possibly produce a shortening of the spectrum. With their along ihe palate, some of which seem to have carried teeth. The order of red three bands were obtainable, for 4 x 0*000527 oral margin was armed with a pleurodont dentition, there being 3 x 0'000703 and = 5 x 0'000422. Three bands were her: on each side about twelve teeth with spatulate crowns, laterally fore possible near E, A, G, respectively. At the conclusiga compressed and serrated. With the exception of the smaller his paper, Mr. Croft directed attention to a very simple fore :) number of the teeth, we have here, on a large scale, a repetition diffraction apparatus, by which most of the ordinary diffracra of the dentition of Iguana. This peculiar skull seems to show phenomena could be well seen, and which also served ""! affinities with both Labyrinthodonts and Lacertilians, and is spectrum observations. Mr. H. Miers pointed out that ri unlike any living or fossil form ; its nearest, though distant, ally Lewis Wright's “Practical Optics” a chart showing the bar apparenily being the Pareiasaurus from the Karoo beds of corresponding to the first four orders of red was given. S South Africa.
far as he was aware, the subject was not fully discussed in Linnean Society, December 1.-Prof. Stewart, President,
book. In reply, Mr. Crost said he had noticed Mr. Wrige in the chair. -A letter was read from the Rev. Leonard Blome
chart, but believed the text implied that the number of his field, expressing his high appreciation of the compliment paid
should be the same as the order of the colour. Tyndall e him by the presentation of the illuminated address which had
definite statements to that effect. - Dr. W. E. Sumpner renta
paper on the diffusion of light. The influence of diffusa been signed by the Fellows present at the last meeting of the Society and forwarded to him.-Messrs. H. and J. Groves ex
increasing the illumination of rooms and open spaces, had? hibited specimens of several Irish Characeæ collected during the
in the author's opinion, been sufficiently appreciated. Ben past summer. Nitella tenussima from Westmeath and Galway
impressed with the great importance of the subject, he was had not been previ usly recorded from Ireland, and a large
to make determinations of the co-efficients of reflection, and
tion, and transmision of diffusing surfaces. To give precs 1 form of N. gracilis from two lakes in Wicklow had been only once previously met with. Referring to the former, Mr. H.
to terms sometimes vaguely used, several definitions were Groves remarked that although it might be expected to occur in
posed. Reflecting power was defined as the ratio of the art all the peat districts it had only been found in two widely
of light reflected from a surface to the total amount of separated localities in England, namely, in the Cambridgeshire
incident upon it ; illumination of a surface, as the amous Fens and in Anglesea.- Mr. A. Lister made some remarks on
incident light per unit of surface ; unit quantity of lights the nuclei of Mycetozoa, exhibiting some preparations under
flux of radiation across unit area of a sphere of unit rates the microscope. - Mr. E. Cambridge Phillips forwarded for ex
whose centre a unit light is placed ; and brighiness as the cas hibition a hybrid between red and black grouse, which had
power per unit area in the direction normal to the surtes been shot in August near Brecon. --Mr. J. E. Harting exhibited
Denoting these quantities by m, I, Q and Brespectively, and made remarks on some coleopterous larvæ which had been
assuming the cosine law of diffusion (i.e. the candle-pored vomited by a child at Tintern, and had been forwarded by the
any direction is proportional to the cosine of the angle between medical attendant, Dr. J. Taylor Brown, for identification. The
the direction and the normal to the surface) it was shows precise species had not been determined, but was considered
# B = m I, and that the average illumination (l') of the 2... to be allied to Blaps mortisaga. Mr. Harting drew attention
a room is related to the illumination (1) due to the direct e. to the fact that cases of voiding colenpterous larvæ were men. of the lights as expressed by the formula I' =' . If tioned by Kirby and Spence (7th ed. p. 71), and by the late Dr. Spencer Cobbold in his work on parasites (1879, p. 269). —
flecting power of the walls, &c., be 50 per cent., . Mr. D). Morris exhibited some tubers of Calathia allonia, eaten
l'= 21, whilst if m=0:8, a number approximately true for w..*| as potatoes in Trinidad, where it is known as Tapee Nambour.
faces, then I' = 51. The illuminarion due to the walls may, 'Ba| Apparently a corruption from the French topinambour (arti.
fore, be far more important than that due to the direct sakses choke). — A communication was read from Mr. J. H. Hart, of the
the lights. When the surfaces consist of portions of de Botanic Gardens, Trinidad, on Ecodoma cephaloles and the
reflecting power, the average reflecting power may be like fungi it cultivates.- Prof. F. Jeffry Bell contributed a short from the equation y ="A1_+ 1A, + &c.. A being the # paper on a small collection of Crinoids from the Sahul Bank,
A North Australia, some of which were new, and Mr. Edgar surface, and Ay, A., &c., the areas of surfaces whose re* Smith communicated descriptions of some new land shells from powers are ni, ng, &c., respectively. This law is short Borneo.— The meeting adjourned to December 15.
quite accurate for spherical enclosures. In measuring replica
power, the surface was attached to a large screen of black Physical Society, December 9.-Mr. Walter Baily, Vice placed perpendicular to a 3-metre photometer bench. President, in the chair.--The Chairman announced that an lights were used, one a Methven 2-candle standard plaen exua meeting would be held on January 13, 1893.-Prof. S. P. the end of the bench remote from the reflecting surface, , Thompson's communication on Japanese magic mirrors was other, a glow lamp of about 20 candle power, was slim postponed.-Mr. W. B. Crost read a paper on the spectra of to a slider which also carried a Lummer- Brodhon photo various orders of colours in Newton's scale. After referring to The glow.lamp served to illuminate the reflecting sure the definition of the order of colours by reference to the retarda. | the photometer was screened from its direct rays. The tion in wave-lengihs, produced by different thicknesses of selenite used in reducing the observations are worked out in the
Percentage absorption a.
1 tables of results given. Absorbing power was determined same pattern, but slightly different in colour, had very different measuring the candle-power of a glow-lamp, first when un effects in producing increased illumination, and wished to know ered, and then when surrounded by a cylinder of the substance if the influence of small differences in colour and texture on der test. It was found to be of great importance to dis- diffusing power, bad been investigated. Mr. Blakesley defended guish between apparent and real absorption, for reflection the cosine law, and suggested that the summation of the powers in the surfaces of the cylinders increases the internal exceeding unity might be due to the fact that the enclosure imination. The true absorption coefficient (a) is given reflected heat as well as light, thus raising the temperature and a = (1 - m) * "1, where n is the reflecting power and ki
increasing the efficiency of the radiant. Mr. Addenbrooke said
the importance of the subject was impressed on him when he 1 kg the candle-powers with and without the envelope of passed through America three years ago and noticed the crude terial under test. In determining transmitting power, the
manner in which electric lighring was there carried out. If thven standard and photometer were placed on one side of using good reflecting surfaces increased the illumination of a surface and the glow.lamp on the other. Difficulties were room 50 per cent., it was like reducing the cost of electricity erienced from the fact that some materials such as tracing from 81. to 4d. per unit. He could hardly conceive any subject er, transmit part of the light directly (like transparent sub of more practical importance than the one before the meeting. nces), and another part by diffusions accurding to the cosine Dr. C. V. Burion did not understand why the cosine law should 1. Methods for discriminating between the different parts be objected to, for it was possivle that no surface was perfectly re therefore devised both in the reflection and transmission diffusive.. The effect of reflection from walls, &c., say in seriments, and consistent results subsequently obtained. illuminating a book would not, he thought, be so great as would bles and curves showing the close agreement of calculated appear from the numbers given, for one usually read near a i observed values, are included in the paper. An abstract of light, and the reflected light falling on the book was only a ne of the tables of numbers is given below :
small part of the whole, on account of the greater distances of the walls. Another member pointed out that in experiments such as those described, it was very important to screen the photometer and surfaces from all radiation other than that under
iest. He rather doubted whether any surface reflected as well Material.
as mirrors. White surfaces might ap ear to do so, but this was probably because the eye would overestimate it, owing to the superiority of white in aiding distinct vision. Dr. Sumpner in reply said he had, as stated in the paper, used white blouting
paper as a standard of reflecting power and found it very conlotting paper ...
venient. His most careful measurements had been made on artridge paper
whitish surfaces and not on coloured ones. Where one colour, racing cloth ...
say red, preponderates in a room, the average light would be racing paper ...
much redder than that emitted by the source owing to the other rdi ary mirror...
colours being absorbed. Io considering illumination as related rdinary foolscap 50 to 70
to distinct vision, it was necessary to take account of the eye issue paper (one thick.
itself, for the pupil contracted in strong lights and opened in ness ... ...
feeble ones. This subject he hoped to treat fully in a subsequent issue paper (two thick
paper. nesses ... ellow wall-paper
Entomological Society, December 7.-Frederick DuCane
Godman, F.R.S., President, in the chair. - The President ark brown paper
announced the death, on December 2, of Mr. Henry T. ellow painted wall
Stainton, F.R.S., an ex-President and ex-Secretary of the lack cloh
Society.--Mr. Jenner Weir exhibited a spec es of Acræa from lack velvet ...
Sierra Leone, which Mr. Roland Trimen, F.R.S., who had irc lamp globes
examined the specimen, considered to be a remarkable variety of Light opal ..
Telchinia enceion, Linn. It was a very close misic of Limnas Dense opal ...
alcippus, ihe usual West African form of Limnas chrysippus. Ground glass
The upper wings of the specimen were rufous and the luwer white, as in the model, and ihe resemblance in other respects
was heightened by the almost total suppression of the black eoretically the sum of the reflecting, absorbing and trans spots in the di-c of the upper wings, characteristic of the usual ting powers should be uniiy, but from the above table it will markings of T. encedon.- Mr. F. J. Hanbury exhibited a renoticed that they exceed 100 per cent., by am junts greater markable variety of Lycæna adonis, caught in Kent this year,
can be accounted for by experimental error. Ths dis. with only one large spot on the under side of each upper wing, pancy, the author thought, might be atıributed to the law of and the spots on the lower wings entirely replaced by suffused nes not being exactly fulfilled. Mr. A. P. Trotter said he white patches. He also exhibited two specimens of Noclua been interested in the subject of diffusion for many years xanthographa of a remarkably pale brownish grey colour, apy a view to obviating the glare of arc lamps. Some experi- | proaching a diriy while, oblained in Essex, in 1891; and its he made on refleciing power gave unsatisfactory results, a variety of Acronycta rumicis, also taken in Essex, with a dark ng, as he now saw, tu his not taking the solid angles sub. hind margin to the fore wings.-Mr. H. J. Elwes exbibited a led by the reflecting surfaces into account. The reflecting living specimen of a species of Cono-ephalus, a genus of Locus. er of substances was of great importance in the illumination tida, several species of which, Mr. McLachlan stated, had been ooms; in one case measured by Dr. Sumpner and himself, | found alive in hot houses in this country. - Dr. T. A. Chapman -thirds of the total illumination was due to the walls. It exhibited immature specimens of Taniocampa gracilis, T. ld greatly simplify measurement of reflecting power if some gothica, T. populeti, T. munda, T. instabilis and 7. leucogratance could be adopted as a standard. Relerring to the pha, which hau been taken out of their cocoons in the autumn, ne law, he said he had found it true, except when the angles with the object of showing the then state of development of the
cidence approached 90°. In cases where consideranle total imagos.-Mr. F. W. Frohawk exhibited a living specimen of ction took place the apparent brigbiness near the normal the larva of Carlerocephalus palæmun (Hesperia paniscus) hy ber
tion was greatly in excess of that in oiher directions. nating on a species of gra-s which he believed to be Bromus je points he illustrated by polar curves. He had also con: asper. The Rev. Canon Fowler and Mr. H. Goss expressed ed what should be the nature of a roughened or grooved their interest al seeing the larva of this local species, the imagos ce to give the cosine law of diffusion. No simple ge -- of which they had respectively collected in certain woods in ical form of corrugations, &c., seemed to fulfil the required Lincolnshire and Northamptonshire. Mr. Goss stated that the itions. Dr. Hoffert said the high numbers given für the loud-plants of the «pecies were supposed to be Plantago major
ting powers of substances were very interesting. Most and Cynosurus cristatus, but that the larva might possibly leed le had noticed the effect of laying a white table cloth in an on Bromus asper.-Mr. C. G. Barrett exbibited a long series iary room. He had also observed that wall papers of the of remarkable melanic varieties of Boarmia repandata, bred