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No. 1402 (vol. xxviii.), pp. 425-460, of the Proceedings be the play or sports of fishes, which probably serves the of the U.S. National Museum contains descriptions by same biological ends as in the higher vertebrates. He Mr. E. A. Mearns of new mammals from the Philippine remarks :-“ Apparently when kept in aquaria fishes only Islands. The most interesting of these is a new genus of sleep during the hours of darkness. If an artificial light insectivore represented by Podogymnura truei. It is allied be thrown upon them they quickly regain consciousness." to Gymnura and Hylomys, and has a long hind-foot and
We have received the annual report for 1903 of the a stout tail rather more than a third the length of head
Government bacteriologist and director of the laboratory and body. Two tupaias are likewise referred to a new
(Mr. H. Watkins-Pitchford), Pietermaritzburg, showing genus, Urogale, one of these having been previously de
| that much good work is being done in the colony. It scribed by Mr. 0. Thomas as Tupaia everetti. They are
contains a valuable bacteriological report on the plague in characterised by the round tail. Several new genera of
Natal in 1902–3. rats are likewise described, for one of which the author proposes the name Bullimus, a term, in our opinion, too The “Nervous Diseases Research Fund” has just issued like the familiar Bulimus. In vol. i., No. 6, of the Bulletin | its first annual report. The object of the fund is to proof the Brooklyn Institute, Dr. J. A. Allen describes a mote and carry on research into the origin and cure of collection of mammals from Beaver County, Utah. diseases of the nervous system. The work is carried on Copies of three other American papers have been received at the National Hospital, Queen's Square, W.C., and is during the current week. In the first, Bulletin of the under the direct supervision of the medical staff of the Brooklyn Institute, vol. i., No. 6, Mr. C. Schaeffer records hospital. During 1904, forty-eight autopsies were peradditions to the beetle fauna of the United States, with formed and the pathological condition investigated. Special notes on some previously known species. In the second, attention has been directed to the study of a disease known Proceedings of the U.S. National Museum, No. 1400, Miss as myasthenia gravis, which is almost invariably fatal, and Richardson describes two new isopod crustaceans from about which little is known at present. California. In the third, op. cit. No. 1401, Mr. T. W. Vaughan gives a critical review of the genera of the
The development of lenticels at points where the stress fungoid corals, with a tentative classification.
is small is discussed by Mr. J. A. Terras in an article in
the Transactions and Proceedings of the Botanical Society WHEN the “ Book of Antelopes " was concluded in 1900
of Edinburgh (vol. xxii., part iv.), and the origin of the authors were unable to give any satisfactory account
lenticels on roots is described in some detail. A first of Heuglin's " giant eland ” of the Bahr-el-Ghazal from
account of new species of flowering plants from the Rethe want of accessible specimens. Heuglin had described
public of Colombia, mostly collected by the writer, who it in 1863, but had based his description on a single pair
accompanied Captain Dowding's expedition in 1898-9, is of horns, and Schweinfurth, who had subsequently met
contributed by Mr. T. A. Sprague to the same number. with the same animal in Bongoland, had given very little A RECENT leaflet issued by the Board of Agriculture and further information about it except that it had stripes on Fisheries furnishes an account of the life-history of the its body. In these circumstances Messrs. Sclater and pine sawfly, Lophyrus pini, which attacks more especially Thomas classed the giant eland of Central Africa as a the Scots pine and the black Austrian pine. Two broods subspecies of the common eland (Taurotragus oryx) under develop in the year, the first in May and the second in the name Taurotragus oryx gigas (“ Book of Antelopes," August. The larvæ are the source of damage, as they it., p. 208). This splendid animal, which may be fairly devour the pine needles. Amongst the animals which feed called "the grandest of all the African antelopes," has on the larvæ are mice, squirrels, goatsuckers, and lately been re-discovered by Mr. A. L. Butler, the super starlings, also numerous ichneumon flies. In plantations intendent of game preservation in the Anglo-Egyptian the best remedy is to kill the larvæ by hand, but as a Sudan, who communicated a full description of it to the spray for ornamental trees in parks and gardens, hellebore Zoological Society at a recent meeting. It appears, from essence or arsenate of lead is recommended. the evidence given by Mr. Butler, that its nearest ally is
ALTHOUGH the investigation of the gametophytes and the Derbian eland (Taurotragus derbianus) of Senegal, and not the typical T. oryx, and he therefore proposes to call
embryo of the gymnospermous genus Torreya has not
yielded the critical results which had been expected, several it Taurotragus derbianus gigas instead of T. oryx gigas. This is probably correct, as the description given by Mr.
interesting taxonomic characters were observed by Dr.
J. M. Coulter and Mr. W. J. G. Land, and are described Butler agrees very fairly in most points with the Derbian
in their account of Torreya taxifolia in the Botanical eland. But the giant eland appears to be a still larger
Gazette (March). The archegonium initial is differentiated and finer animal, with much stronger horns; its height at the withers is stated to be 68 inches. On this question we
very early, while most of the endosperm develops after
fertilisation. A pro-embryo of twelve to eighteen cells may shortly have an opportunity of forming an opinion, as
completely fills the egg and persists through the winter, Bimbashi Collins, of the Egyptian Army, who has himself
until in the spring the suspensor elongates, and later the shot two specimens of the animal, has sent the heads and
ruminated appearance of the endosperm becomes apparent. skins to Mr, Butler to be forwarded to England, where
Rumination is shown to be due to the unequal resistance they will probably go to the Natural History Museum at
offered by the perisperm in different parts of the seed to South Kensington.
the encroaching endosperm. The question of the sleep of fishes was referred to The report of the Meteorological Commission of Cape p. 104) last week in our notice of the last volume of the Colony for the half-year ending June 30, 1904, has been "Cambridge Natural History." Mr. F. Davis, writing received. The usual tables of rainfall, temperature, &c., from 49 and 51 Imperial Buildings, Ludgate Circus, E.C., 1 at various stations will not be published until the issue of says that observations of many varieties kept by him in the next half-yearly report, so that the data may be comaquaria extending over a period of twenty years show that parable with the information contained in previous yearly Ashes do sleep. He has also observed what appeared to l reports. But in lieu of the usual tables above referred to, the present issue contains a very valuable series of twenty-| observatory could be heard in the telephone receiver, the three tables prepared by the secretary (Mr. C. M. Stewart) i operator at the sending end merely counting one or two showing the characteristic features of the winds at the beats. On May 25 the destroyer Escopette, whilst at Brest, Cape Observatory during the five years 1896-1900, arranged was able to regulate its chronometers directly against the under sixteen points of the compass, and referred to various standard clock of the Observatory of Montsouris with an elements, e.g. temperature, humidity, &c., and giving the accuracy of about on to 0.2 secoud. As M. Guyou points percentage of relative wind-frequency and wind-force at out, owing to the wide extent of the telephone system at various hours.
the present time, this mode of transmitting the time ought We have received a copy of the report of the director of
to be of considerable service. the Philippine Weather Bureau for the year ending August
IN Kungl. Svenska letensk. Akad. Handl. (Band 38. 31, 1904 (reprinted from the report of the Philippine Com- No. 5) Dr. Hasselberg gives the results of an investigation mission, part ii.). We have frequently had occasion to of the arc spectrum of tungsten. The region he has studied refer to the useful work of this organisation, and the extends from 1 3477 to 5892. This is a continuation of valuable researches and publications of the Rev. J. Algué, the very useful series of publications by the same spectroS.J., particularly in respect of the cyclones in the Far East. scopist relating to the arc spectra of metals. The eliminThe central office performis a large amount of work ation of lines due to impurities was done by comparing the gratuitously for observers on land and sea, by adjusting
tungsten spectrum with those of other metals taken under and comparing instruments; this is generally only known
similar conditions. In cases of close agreement between to those benefited. The director states that the weather
tungsten lines and those of other metals a special study bureau is never closed; the chief officials live at the observ was made of the lines with the object of establishing their atory, and are ready to attend any call at all hours, coincidence or non-coincidence, and in the former case the especially inquiries by officers of ships, if they wish for
probable origin of the common line was determined from information as to the conditions of weather. In addition
a consideration of the relative intensities in the two spectra. to the regular work, telegrams are constantly exchanged
In a comparison column are given the lines recorded by between the provinces, China, Formosa, and Japan, and
Messrs. Exner and Haschek for the same element. The when bad weather is impending special warnings are dis
strongest lines of this metal have been carefully compared patched to the points threatened.
with the Fraunhoferic lines, and cases of coincidence and
probable identity noted. The annual summary of the Monthly Weather Review of the U.S. Weather Bureau for 1904, containing a useful
In our issue of July 28, 1904, we noted that Dr. H. M. subject, author, and title index of the papers published
Reese, of Yerkes Observatory, had published the results in the monthly parts, and an annual climatological
of some observations of “ enhanced ” lines in the Fe, Ti, summary of the observations made at the Weather Bureau
and Ni spectra, wherein he supposed that he had disstations, has just reached us. Weather
covered some enhanced lines not included in Sir Norman
forecasts for thirty-six and forty-eight hours in advance have been
Lockyer's lists. In the current number of the Astromade daily throughout the year for each State, and special
physical Journal Mr. F. E. Baxandall comments on Dr. warnings of gales on the sea coasts have been issued
Reese's results, and shows that in a great number of cases when necessary. In a number of instances, the chief of
there is no evidence of enhancement in the Kensington the Weather Bureau states, European shipping interests
photographs. For example, the comparative tables given were notified of the character and probable course of severe
show for each element that of the seventy enhanced lines storms that were passing eastward from the American
discovered by Dr. Reese íor iron, fifteen are actually coast. The warnings and indications of the movements of
stronger in the are than in the spark spectrum, twentyWest India hurricanes have evidently been the means of
five are equally strong in both spectra, twenty do not occur saving a large amount of property and a number of lives,
in either spectra on the Kensington grating spectrograms, and their value has been acknowledged by the Press, and
whilst six are so slightly "enhanced " as to leave it also by the President of the Jacksonville Board of Trade,
doubtful as to whether they should be included in this who states that the warnings to vessels not to leave port
category. It seems probable that Dr. Reese was misled prevented serious disasters. Prof. W. L. Moore expresses
by comparing two spectra of which the spark was generally the hope that the time will come when it will be possible
the stronger, for he especially remarked that only one line to forecast the weather generally for coming seasons, but
was stronger in his are than in his spark spectrum. that time has not yet arrived. Valuable researches are We have received from the Bureau of Mines of Ontario being made at Mount Weather Observatory, Virginia, | an interesting memoir on the limestones of the province where it is proposed, inter alia, to discuss meteorological by Mr. Willet G. Miller, the provincial geologist. It observations from the point of view of their relations to covers 143 pages, and contains a number of excellent solar physics, and to select meteorological and magnetic photographs of the principal quarries. It shows clearly elements and compare them with solar observations. where limestones of various chemical compositions are to Is the current number of the Comptes rendus of the
be found, and gives a concise account of the uses of lime. Paris Academy of Sciences M. Guyou gives an interesting
stone and lime at the present time. Hitherto it has hardly account of the utilisation of the telephone system
been realised that limestones form an important part of
for the exact transmission of time. The experiments were under
the mineral resources of Ontario, and this well arranged taken by the Observatory of the Bureau des Longitudes
collection of analyses of limestone and of descriptions of at the request of the Chambre syndicale de l'Horlogerie,
quarries cannot fail to prove of value to all interested in and after a preliminary trial in the Paris area were ex
the important industries that depend upon limestone as a tended to the whole French system.
The transmission of the time by a verbal signal not being sufficiently exact for MESSRS. ILIFFE AND Sons, LTD., have published a little the purpose, by means of a specially arranged microphone book on practical frame-making by Colonel W. L. Noverre; each beat of the pendulum of the standard clock in the the price is is, net.
OUR ASTRONOMICAL COLUMN. and 7 per cent. of the total respectively, nine-tenths of PHOTOGRAPHIC REALITY OF THE MARTIAN Canals.-No.
them being within 30° of the galactic equator. A
congregation in certain galactic longitudes is also 4021 of the Astronomische Nachrichten contains a telegram
indated May 28 from Mr. Lowell to Prof. Pickering in
dicated. Thus between 160° and 340° there are 613, or which the former states that several of the canals on Mars
78 per cent. of the total, of these stars. About one-quarter have been photographed by Mr. Lampland. Amongst
of the whole number are contained in four regions having others, Nilo Syrtis, Casius, Vexillum, Thoth, Cerberus,
a total area of 790 square degrees, or less than one-fiftieth Helicon, Styx, Chaos, and Liedeus (? Libneus) are shown
of the sky. One of these four regions is near to the
variable star I Carinæ, and lies almost wholly within the on the negatives, some appearing on more than twenty
constellation Argus. As this Argus region contains nearly plates.
three times as many “ Orion " stars as does the Orion DISCOVERY OF SATURN'S TENTH SATELLITE.—A brief note
region, Prof. Pickering suggests that “ Argus" stars in No. 4015, of the Astronomische Nachrichten states that
would have been a more suitable generic name for the Saturn's tenth satellite was discovered from an examin
class of stars having spectra of thiş (B) type. He states, ation of several plates taken with the 24-inch Bruce tele however, that the nebula of Orion appears to be the startscope which were selected from those used in the deter ing point, or origin, of class B stars, twenty of which are mination of the orbit of Phæbe.
situated within 1° of a Orionis, that is to say, nearly as The new satellite appears on thirteen plates. The
| many as are contained in the region between galactic orbital motion is direct and the period is twenty-one days, latitudes +30° and +90°, although the area of the latter therefore the satellite is apparently a little nearer to Saturn region is three thousand times as great. than is Hyperion.
Arranging them according to magnitude, it is found that JUPITER'S SIXTH AND SEVENTH SATELLITES.-An abstract most of this class are bright stars, only 1 in 20 being of
of the Publications of the Astronomical the sixth or fainter magnitudes. Society of the Pacific, appearing in No. 4015 of the Astro THE MOTION OF THE TAIL OF BORRELLY'S COMET (1903 iv). nomische Vachrichten, contains an account by Prof. Perrine -From the examination of a number of photographs of the observations so far made of Jupiter's sixth and obtained by different observers during July, 1903, Prof. seventh satellites.
Jaegermann, Moscow, has compared the relative motions The former can be photographed in ten minutes with of the different sections of the tail of comet 1903 iv in the Crossley reflector, and thirty-six plates have been
regard to the movements of the comet's nucleus and to obtained. A preliminary investigation of the orbit shows
the sun. After analysing the velocities and movements dethat the inclination to the ecliptic and the planet's equator termined, he has arrived at the conclusion that in this is about 30°, and that the satellite has a period of about
case light-pressure, acting in the sense of Arrhenius's 250 days, with a mean distance from the planet of 7,000,000
hypothesis, was not the determining factor in the formation miles. The direction of the orbital motion still remains
of the several tails, for a pressure sixty times greater than uncertain. The brightness of the satellite indicates a gravity would have to be assumed. If the light-pressure diameter of about 100 miles, or less.
hypothesis be retained, the assumption must be made, On examining the plates taken for the sixth satellite according to Bredichin's idea, that the tail-matter conon January 2, 3, and 4, a much fainter object, also
sisted of gaseous molecules, and that its illumination was apparently belonging to Jupiter, was discovered, which was due to the Auorescence of highly illuminated gases, such then situated N. and W. of, and was moving towards, the
as has been experimentally demonstrated by Lommel, planet. Subsequent observations, which, owing to the
Wiedemann, and Schmidt. satellite's faintness, were much more difficult to make than
The existence of a repulsive force, other than lightin the case of the sixth satellite, confirmed its dependence
pressure, was demonstrated by Bredichin in comet upon Jupiter. This object was not shown on the negatives Rordame (1893 ii), by Prof. W. H. Pickering in comet taken for the sixth satellite during December, being just Swift, and was confirmed by Prof. Jaegermann in a preoutside their field, but altogether twenty observations have liminary investigation concerning the denser parts of the been made, the last on March 9.
tail of comet Swift, 1892 i. Apparently the orbit of the seventh satellite is quite
Double Star OBSERVATIONS.—The results of a series of eccentric, with a mean distance from the planet of about 6,000,000 miles and a period of about 200 days. The
observations of double stars made at Kirkwood (Indiana) inclination of the orbit to the plane of Jupiter's equator
Observatory are given in No. 4022 of the Astronomische is about 30°, but the direction of the orbital motion is
Nachrichten. The observations were made by Mr. J. A. as yet undetermined. The photographic magnitude of the
Miller and Prof. W. A. Cogshall with a 12-inch refractor, seventh satellite is not brighter than the sixteenth, and
and the B.D. and A.G. numbers, the 1875 position, the on comparing this with the magnitudes of other satellites
magnitudes, and the measured position-angle and distance and of asteroids a diameter of about 35 miles is deduced.
are given for each of 114 double stars. Prof. Perrine suggests that the large inclination of their
The objects observed were selected from those noted as orbits indicates that neither of these bodies were originally
double by the Leipzig observers when preparing the A.G. members of Jupiter's family, but have been “ captured "
?, catalogue for the zone +10° to +15°, and, with few excepby the planet.
tions, they have not been measured elsewhere. Some few STARS WITH SPECTRA OF THE ORION TYPE.-In No. 2,
stars suspected by the Leipzig observers as duplicate could tyl. lvi., of the Annals of the Harvard College Observatory,
not be seen as such by the Kirkwood observers, and one the distribution of stars having class B
or two of the sets of measures refer to newly discovered
or Orion-type 1 double stars. spectra is discussed, and all known stars of this type placed in a catalogue, in order of R.A., the position 11900), magnitude, exact type of spectrum, and the
THE ROYAL OBSERVATORY, GREENIIICH. alactic longitude and latitude being given for each star. ON Saturday last, June 3, the Board of Visitors made Consderably more than 30,000 spectra have been examined V their annual inspection of the Royal Observatory, bu Mrs. Fleming in connection with the Henry Draper | Greenwich, but unfortunately, through ill-health, the **j* trial work, and of these 803 are included in the pre- | Astronomer Royal was not able to be present. The followet catalogue.
ing is a brief abstract of the report which was submitted As a distinctive feature of these stars is the helium to the visitors. Diu atrd in their spectra, the allocation of them with | Very great progress has been made in the observation pogard to galactic longitude and latitude really indicates of the reference stars for the Greenwich section of the
distribution of helium in the universe. On thus | Astrographic Catalogue, about 9500 observations of R.A.
sifying them, it is found that on dividing the sky into and N.P.D. having been added during the year. The Pual array the galactic latitudes of which are included comparatively few observations required to secure five ir tween +90° and +30° +30° and oo, oo and -- 30°, and observations of each of the reference stars (more than
IP and -90°, the numbers of well marked helium stars 10,000 in number) will easily be obtained by the end of 13 these divisions are 22, 219, 509, and 53, or 3, 27, 03, | the year, as there are only 5 stars requiring three observations, 100 requiring two, and 1500 requiring one observ | 83o and the pole. The number of plates measured up to ation only in order to carry out the programme. In fact, the date of last year's report was 1051. Adding the 102 it may be taken that the observations for this catalogue
plates measured this year, the total number of plates are practically completed. The catalogue, which will be measured is 1153, being the 1149 of the Greenwich section terminated this year, will contain, besides the reference
+ 4 additional photographs of the polar field. stars for the Astrographic Catalogue, the 834 zodiacal For the year ending 1904 December 31, Greenwich photostars given in the Nautical Almanac for 1897.
graphs of the sun have been selected for measurement on It is proposed to begin next year a new nine-year cata
209 days, and photographs from India and Mauritius (to logue of the stars of magnitude 9.0 and brighter between fill up the gaps in the series) on 151 days, making a total the limits +24° to +32° of N. declination, this being the of 360 days out of 366 on which photographs are at Oxford astrographic zone, for which they serve as refer present available. Photographs were taken in Mauritius ence stars. The re-observation of these stars, which for for three of the six days yet unrepresented, and may be the most part fall within the Cambridge zone of the received in due course. Astronomische Gesellschaft Catalogue, will afford valuable The solar activity has shown a great increase during data for their proper motions, besides giving fundamental
the year ending 1905 May 10, and the sun has not been positions for the Oxford astrographic plates.
free from spots on a single day during that period. The The comparison between theory and the Greenwich
mean daily spotted area for 1904 was more than half as meridian observations of the moon from 1750 to the present great again as that for 1903, and early in the present year time, undertaken by Mr. Cowell, has been completed for a number of exceptionally large groups was observed. the longitudes, and the discussion from 1847 to 1901 is The group which was seen first on the cast limb on 1905 completed for the latitudes. The only point left outstand January 28 had a greater total area than any other group ing is the motion of the node, for which it is necessary which has been photographed at the Royal Observatory. to discuss as long a series of observations as possible. The principal results of the magnetic elements for 1904 The results obtained for the longitudes are summarised in are as follows: a series of papers in the Monthly Notices of the Royal
Mean declination ... ... ... 16° 15'o West.
( 4'0166 (in British Units).
Mean horizontal force ... 1.8520 (in Metric Uniis). terms as obtained directly from observation, with a comparison with the theoretical coefficients given by Hansen,
Mean dip (with 3 needles) ... 66° 57' 11". Delaunay, M. Radau, and Dr. Hill. The publication of In 1904 there were no days of great magnetic disturbance the details of the whole investigation will be shortly and eight of lesser disturbance. proceeded with
The mean temperature for the year 1904 was 499.8, or The re-reduction of Groombridge's observations was | 0°.3 above the average for the fifty years 1841-90. During completed at the date of the last report, and during this the twelve months ending 1905 April 30 the highest year the printing of the results has been pushed on. The temperature in the shade (recorded on the open stand in introduction has also been prepared for press. A dis the magnetic pavilion enclosure) was 91°0, on August 4. cussion of the proper motions determined by comparison On the same day the highest temperature in the Stevenson with modern Greenwich observations, and a determination screen in the magnetic pavilion enclosure was 89°:5, and of the constant of precession and of the direction of the in the observatory grounds 89°:7. The lowest temperature solar motion by Mr. Dyson and Mr. Thackeray, are given of the air recorded in the year was 19o.5, on January 1. in the Monthly Notices of the Royal Astronomical Society, During the winter there were thirty-nine days on which March.
the temperature fell below 329.0, being seventeen less than The altazimuth has been in regular use throughout the the average number. year, and a second determination of the pivot errors has The mean daily horizontal movement of the air in the been made, and also observations for obtaining the value year ending 1905 April 30 was 280 miles, which is 2 miles of one revolution and errors of the screw of the telescope below the average of the preceding thirty-seven years. micrometer have been completed.
The greatest recorded daily movement was 867 miles, on The observations of the moon, both in and out of the November 9, and the least 49 miles, on December 22. meridian, seem very satisfactory as shown by the agree The greatest recorded pressure of the wind was 23.5 1b. ment between the two instruments, the transit circle and on the square foot, on March 12, and the greatest hourly the altazimuth.
velocity 45 miles, on December 30. The 28-inch refractor has been employed, as was the The number of hours of bright sunshine recorded during case last year, for micrometric measurements of double the twelve months ending 1905 April 30, by the Campbellstars, the total number measured being 603. Of these, 143 Stokes instrument, was 1486 out of 4457 hours during have their components less than 1".0 apart, and 60 less which the sun was above the horizon, so that the mean than 0".5. A marked deterioration of the images of the proportion of sunshine for the year was 0-333, constant stars led to an examination of the lenses, and the suspected sunshine being represented by 1. tilt. between the components was corroborated and The rainfall for the year ending 1905 April 30 was remedied.
20-21 inches, being 4.33 inches less than the average of the Sixty-five photographs of Neptune and its satellite have fifty years 1841-90. The number of rainy days was 153. been secured with the 26-inch refractor, while, with the This small rainfall may be contrasted with the heavy 30-inch reflector, numerous photographs of minor planets rainfall of 35-42 inches in the corresponding period last and comets a, b, c 1904, and a 1905, have been obtained. year. The most striking contrast is obtained by com
At the date of the last report, 119 plates taken of Eros paring the rainfall for the year commencing 1903 March 1, with the astrographic equatorial, and 55 taken with the which was more than 37 inches, with that for the year Thompson equatorial, had been measured. During this commencing 1904 March 1, which was less than 17! year the remainder of the photographs have been measured, | inches. This dry period of twelve months was followed making in all 198 with the astrographic equatorial and by a heavy rainfall in 1905 March, which exceeded 31 152 with the Thompson instrument. The reduction of the inches, and is the greatest amount recorded in March since measures is in a satisfactory state, and it is expected that | 1851. it will be completed in two months for both sets of The printing of the Paris-Greenwich longitude deterphotographs.
mination, 1902, is practically complete. The Killorglin The astrographic equatorial has been employed mainly | longitude is the only determination which still requires to to obtain photographs to replace chart plates which show be printed to complete the volume of longitude determinslight photographic defects unsuitable for production of ations, which will contain the determinations Paris-Greenenlarged prints.
wich made in 1888, 1892, and 1902, of GreenwichThe measurement of the catalogue plates for the Green- | Waterville-Canso-Montreal made in 1892, and of Greenwich section is now completed. Since the last report | wich-Killorglin made in 1898. 47,200 measures of pairs of images (6m. and 3m.) have The re-reduced Groombridge Catalogue is nearly combeen made. The number of plates measured in the year pletely printed, with the exception of the introduction, is 102, covering 128 square degrees between declination which is ready for the press.
Provision has been made in the Navy Estimates for the ness of glass removed by polishing and by etching with observation of the total solar eclipse of 1905 August 30 | hydrofluoric acid under various conditions were illustrated. by a party of three observers on the coast of Tunis, where In the discussion Mr. Walter Rosenhain cited evidence to the weather conditions are promising. It is proposed to show that the surface flow which has been recognised in take photographs of the corona for detail and extension the polishing of metals also occurs in glass. with the Thompson 9-inch coronagraph, the 13-inch astro Mr. Walter Rosenhain dealt with the possibilities of graphic refractor, and the 4-inch Dallmeyer rapid recti progress in optical glass; he described the limitations to linear lens, and also photographs of the spectrum with the production of vitreous fluxes of extreme properties, and the two spectroscopes lent by Major Hills, R.E., as in advanced the view that media of widely different optical 1900 and 1901.
properties could only be obtained by the production of large homogeneous crystals. Physicochemical considerations were cited to indicate lines upon which this difficult problem
might be solved. THE OPTICAL CONVENTION.
A number of instruments for optical measurements were THE optical convention has just concluded a very described, Prof. Poynting exhibiting his form of parallel
successful meeting extending over four days; the plate micrometer. Mr. Blakesley described his apparatus exhibition and the papers attracted numerous visitors from for the measurement of focal length of lenses, with appliall parts of the country. The papers led to much valuable cations to other optical measurements. Mr. Chalmers dediscussion. An account of the exhibition and the presi scribed a new form of refractometer for obtaining the dent's address appeared in last week's NATURE.
refractive index of glass in lens form. The lens is inserted The first group of papers dealt with the design of in a trough containing a suitable transparent liquid, and optical and scientific instruments. The Gauss theory | the difference of the refractive indices is deduced from the was entrusted to Mr. Conrad Beck, who considered the approximate curvatures of the lens and its power in the theory of the equivalent planes of complete optical instru liquid, with an accuracy comparable with that of the best ments; he dealt more particularly with the complete refractometers. microscope in relation to its “ working distance."
Mr. Baugh described the use of invar tapes for baseDr. Drysdale gave a general account of the aberrations line measurements. of lens systems, submitting a classification and specifi Dr. Drysdale discussed the requirements of small telecation of the various aberrations to obtain an expression scopes and binoculars, with special reference to the field of opinion from those working at the subject. Mr. of view and illumination of the image. He indicated the Chalmers gave a graphical method of representing the method he had employed in calculations for prism faults of calculations of lens systems, and a modification binoculars, showing how he had been led to use glass of of the Hartmann system of testing to permit of measuring high refractive index for the prisms. He described a special and expressing aberrations in exactly the same form. form of photometer for determining the absorption in This should make it possible to obtain the relation between binoculars. the definition and the measured or calculated aberrations. Mr. A. C. Jolley gave a critical review of photometric in the discussion Mr. Carson pointed out the importance standards and apparatus; he described a modification of of the relative intensity of the image disc and the aberration the Violle platinum standard, and discussed the difficult patch in estimating the performance of lenses.
problems connected with heterochromatic photometry ; his Mr. Walter Rosenhain criticised the mechanical design results indicate that the accuracy claimed by Sir W. Abney of certain types of instruments; he showed that, in many is far too high, especially when readings by different cases, the ideals of the instrument maker were in conflict observers are compared. He concludes that a discriminwith sound engineering principles, and suggested directions ation photometer is the most trustworthy instrument for in which improvements might be looked for.
comparing different colours. Diffraction in optical instruments was discussed by Mr. Mr. Milne exhibited his new form of spectrophotometer. I W. Gordon in an important theoretical paper ; his con The apparatus is especially suitable for determinations of clusions, which would modify many of our ideas on optical the absorption of light of specified wave-length by liquids. Sitems, are now being submitted to a definite experimental Mr. Bull discussed the theory of tricolour filters, plates, Dest.
and inks. He concluded that it was most satisfactory to group of papers related to interference phenomena. | adjust each independently of errors in the adjustment of Mr. J. Rheinberg exhibited a method of producing achro- the others. The filters should have a certain amount of mafic interference bands which is likely to have numerous overlap, the colour of the overlap of two filters being the applications. Mr. Stansfield described a simple form of colour of the printing ink corresponding to the other Vichelson interferometer specially suitable for demonstra- | filter. I on. Prof. Watkin and Mr. Morrow exhibited their
Mr. Crawley discussed the limits of stereoscopic vision ; apparatus for calibrating extensometers by observing the the results of his measurements point to a much greater displacement of interference bands.
accuracy in judging distances by stereoscopic effect than Mr. Twyman described the manufacture of the Echelon | is generally admitted. spectroscope, stating the accuracy required in the plates
Mr. H. L. Taylor discussed the effects of astigmatism and the precautions used to obtain it. This apparatus on the accommodation of the eye. Two new forms of wd exhibited and compared with the Lummer“ parallel
ophthalmometer were demonstrated, one being the Ettlespalate " arrangement for obtaining resolution of spectrum
Curties, which is valuable for the perfection of its Inong Mr. Blakesley discussed the various forms of prism
mechanical adjustments, and the use of complementary which could be used in constant deviation Spectroscopes
colours for the mires; it is so arranged that the corneal and some of their applications. Mr. Newall dealt with microscope can be readily attached. The ophthalmometer astronomical spectroscopes, demonstrating that the limits shown by Mr. Sutcliffe contains a number of variations of usefulness of the present type of spectroscope were
from ordinary forms; the mire is an almost complete ring almost reached in the case of faint stars, as the intensity
illuminated by a special lamp, and the method of doubling of light necessary for photographing their spectra can only
the image is novel. Piyus obtained at the sacrifice of the purity of the spectrum
Dr. Walmsley gave an account of the attempts which at the certainty of identification of the lines, and that no
have been made to provide technical education for those Yory marked improvement is likely to be obtained from
engaged in the optical industry, and the existing facilities; "he tim of larger objectives, on account of the increased he outlined the scheme for the establishment of a British ahsorption in the prisms required. He suggested the use
Institute of Technical Optics. The convention decided to ex gratings.
memorialise the London County Council to support the Lord Rayleigh dealt with the subject of polish, pointing scheme. Pasit the distinction between the process of grinding, which
Major-General Waterhouse gave an account of the history innsists of the removal of comparatively large flakes, and of telephotography.
at ol polishing, which he regards as molecular, the rough. In the evening lecture, Prof. Silvanus P. Thompson gave Dess of the surface being reduced to dimensions smaller a most interesting account of the various forms of Nicol's han the wave-length of light. Experiments on the thick prism and its modern equivalents,