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2 + Cyx - Cy = 0, if A = - 27C32 + 18CC,C3

THE BRAIN IN MUDFISHES. - 40,3 + 6*6*, S = 20;3-9C,C, +27C3, T = 9C3 | Das Centralnervensystem von Protopterus annectens; the relations in question are

eine vergleichend Anatomische Studie. Von Dr. Rudolf =-274, V.,3 = }(5 + V3), V3 = }(S V3); Burckhardt. (Berlin: R. Friedländer und Sohn, 1892.) 1 = x1 + wʻx, + WX3, V, = xi + wx, + w*x3,

THE Mudfishes, Dipnoi, from many peculiarities in 7+ 3(x72x3 + xoʻx1 + xz>r,) + 3^2(x2+x2 + x,?r3 1 their structure, have attracted the especial attention + x3+xz);

of anatomists and zoologists. Important monographs C +1, + V2, x, = }{G+wV2 + w2V2}, on Lepidosiren have been written by Owen and Wieders3 = }{C + wa V, +wVz.

heim, whilst Huxley, Günther, and Beauregard have ns of this theorem and certain elementary prin- described the anatomy of Ceratodus. Serres, in 1863, ( the theory of substitutions an elegant and simple made a contribution to the anatomy of the nervous tration can be given of Abel's theorem that the system of Protopterus, Fulliquet in 1886, and Parker in

by radicals of the general equation of the nth 1888, have also added to our knowledge of its strucs impossible when n > 4: see $ 217 of the work ture; and now Dr. Burckhardt has published a well

illustrated monograph on the central nervous system of ugh the theory of substitutions bears, as we have Protopterus annectens. He had obtained an ample wn, on some of the oldest and most interesting of supply of this fish from Herr W. Jezler, a merchant blems of algebra, it has been comparatively little whose business engagements had taken him to the

especially by English speaking mathematicians. neighbourhood of Bathurst, Senegambia. On more than e has therefore rendered us a service of great one occasion Dr. Burckhardt had received living fish, so nce by translating one of the standard treatises that he was able to study the microscopic anatomy by subject. Of the three that were at his disposal the use of the most recent technical methods, and has k that he has chosen the one most likely to be thus added materially to our knowledge of the brain of o a beginner. While Serret in his “Higher this animal. " and Jordan in his “ Traité” treat the theory The author found, in the anterior horn of grey matter i abstract and more general point of view, Dr. of the spinal cord, remarkably large nerve-cells, which constantly associates with the substitution the possessed both branching protoplasm processes and an

on which it is supposed to operate. This gives axial-cylinder process. In the lateral and posterior horns ful concrete aid to the comprehension of the pro- nerve-cells somewhat smaller in size were seen. The s of the abstract theory and also helps the student medulla oblongata gave origin to nerves which he names

their application. The great danger in subjects hypoglossal, vagus, glosso-pharyngeal, acusticofacialis, generality is that the stream of theorems is apt to and trigeminus. He also describes two slender nerves as the mind of the learner without soaking in, like abducens and trochlearis, so that the Dipnoi are not, as f the proverbial duck's back.

some have said, destitute of these nerves. The cereletto's book will be found to contain all the ordi bellum formed the anterior boundary of the 4th ventricle. orems regarding the classification of substitutions, Large nerve-cells, corresponding to those of Purkinje in existence of groups, transitive and intransitive, the mammalian brain, were not seen. The mid-brain was e and non-primitive, simple and compound; the distinct, and gave origin to a root of the trigeminus, to of the algebraic relations between the values of the optic tract and to the oculo-motor nerve : grey matter --valued functions and between functions belongs containing nerve-cells was grouped around the aqueduct r included in the same family; and also a con- of Sylvius. e number of theorems regarding special groups. Whilst Protopterus corresponded closely with the plications embrace the theory of resolvents in lowest vetebrates in the regions of the mid and hind and of the Galois resolvent in particular; the brains it presented striking peculiarities in the pineal theory of the solvability of equations by means of region. The roof of the 3rd ventricle was complicated, ; the theory of the group of an equation and a and possessed a velum, which represented a middle on of the criteria of solvability; besides special choroid plexus ; a conarium, and a structure like that ions to the cyclotomic and Abelian equations, and which Edinger has named “ Zirbelpolster.” The epiphysis tions three roots of which are connected by a (Zirbel) was attached to the skull by the arachnoid relation.

membrane. ranslation has been admirably done, both from The fore brain was well developed, and divided into uistic and from the mathematical point of view. two hemispheres. He recognized in it a posterior ventral d, it is true, here and there passages which were swelling, which, because it contained cells similar to at obscure ; but in every case, on comparing with those found in the dentate gyrus (fascia dentata) of the inal, we found the rendering to be absolutely higher brains, he describes as a lobus hippocampi. He

Such obscurities therefore must be charged distinguished a fissure which separated the lobus olfacthe author, or to the nature of the subject, or to torius from the pallial part of the hemisphere, so that he syncrasy of the critic, and not to the translator. harmonizes the fore brain in its fundamental divisions gratulate Mr. Cole on the successful completion with the mammalian brain as described by Broca and rduous task, and heartily recommend the result Turner. He directs attention to an elevation ventrad

lover of the most ancient and the most beautiful of the lobus olfactorius, which he calls the lobus poste sciences.

G. CH. olfactorius. This lobe is also found in the brains of Selachia and Amphibia, and apparently corresponds to has, however, the disadvantage that it destru the lobus olfactorius posterior described by His in the

tinuity. Many of the paragraphs are necessar. human embryo, which forms the anterior perforated spot

and one passes from one subject to another with a

amount of abruptness. The style of the writing in the adult human brain. As regards its structure the

ever, interesting and clear, so that this disadva hemisphere possessed central grey matter containing reduced to a minimum. The parts that treat toe nerve-cells which lay around the hemisphere ventricle; in a fuller style, such as those in which fermez: also a mass of grey matter which he calls corpus striatum; the origin of urea in the economy, or the it. I whilst in the more posterior part of the ventral region of

hæmoglobin to bile pigment are discussed, are 1

i lucid writing. the hemisphere were nerve-cells which represented a : “The bor

hich represented a The book opens with a description of the prett cortical layer. In the dorsal region of the hemisphere ferments, the most important of physiological sch also cortical nerve-cells were found, which were arranged but those of which, from the chemical standpu as an inner and an outer layer. The cells of the cortex know least. The simpler materials found in the e gave origin to nerve fibres. A definite anterior com- its excreta are treated next. This is the more i

part of the book, and the author expresses his : missure was present, the fibres of which passed on each

ness to Dr. S. Ruhemann for assistance here. On side into the lobus hippocampi. Burckhardt, also, figures, whether this part of the work will prove attra as distinct from the anterior commissure, fibres which he ordinary students. There is no question that al regards as the corpus callosum of Osborn. The most students should be educated up to it, but a important tract of nerve fibres was the basal bundle. i organic chemistry and structural formulæ are

they are inclined to fight shy of. The concluding: which ascended from the spinal cord into the corpus

are again devoted to substances of which se striatum.

physiological rather than a chemical knowledge One of the most interesting chapters in Burckhardt's the pigments. memoir is that in which he gives an account of the saccus The figures of crystals, which form a new feat endolymphaticus. Wiedersheim had described in 1876, present edition, have been taken from the e in Phyllodactylus europaus, a sac with many branching

Krukenberg, Kühne, and Funke. One canno:

, this notice without alluding to the extensive re diverticula, filled with otolith-sand and lying in relation

on

to liter

to literature that are given throughout. This to the choroid plexus of the 4th ventricle. Hasse had a most valuable assistance to all original workers previously seen in Amphibia a similar structure which those more earnest students who desire to go dee Coggi had investigated in the frog. Burckhardt has for the subject. The references are provided with as the first time observed and figured it in Protopterus. The

index. They are chiefly to German literat saccus comniunicated by a narrow neck with the sacculus

German leanings of the author are seen a

spelling of sarkosin, kreatin, &c. The final s and utriculus of the auditory vesicle, and with its diver

omitted in the names of the amido acids. It wo: ticula overlaid the region of the 4th ventricle, and ex good thing in the future if international unifores tended as far back as the 1st pair of spinal nerves.

names of chemical compounds were adopted The memoir contains a short chapter on the phyletic

| meantime it seems a pity that Dr. Lea has es development of the brain of Protopterus. Starting with

to use the spellings reconīmended by the Chennai

of London. Selachia, he considers that one line of development has The author is to be congratulated on having been through Protopterus to Ichthyophis, and thence to his labours to a successful conclusion, and so the Urodela and Anura; another through Ceratodus to the present volume no better compliment that Reptilia and Mammalia ; whilst a third line is from the that it is well worthy of those that have precede Selachia to the Ganoids and Bony Fishes.

Chambers's Encyclopædia. New Edition. Voll |

and Edinburgh : W. and R. Chambers, 1892 OUR BOOK SHELF.

The editor and publishers of the present work The Chemical Basis of the Animal Body.

cordially congratulated on the fact that it has a

An Appendix successfully completed. A better encycloppis to Foster's “ Text-Book of Physiology" (fifth edition).

on). scope does not exist in our own or any other By A. Sheridan Lea, M.A., D.Sc., F.R.S. (London:

Nominally it is merely a new edition ; but in Macmillan and Co., 1892.)

the editor claims in the preface, it must be to, LIKE its parent volume, this well-known appendix has to all intents and purposes a new work. One at: grown in bulk considerably, so that it now constitutes a' difficulties in an undertaking of this kind is tos treatise (separately paged and indexed) on the chemical each subject shall have the degree of attention substances occurring in the body. It contains numerous properly belongs to it, no single subject or gres references to the text of Foster's “ Physiology," and so the jects being permitted to usurp space which ouça two may be most profitably read together.

otherwise occupied. The editor has grappled The plan pursued in the present edition is the same as i difficulty so effectually that few readers will hare! in former editions; the chemistry of the body is described to complain of any lack of proportion in the lo under the headings of the names of the chemical sub- various articles. Another striking merit of the stances. This plan has its advantages. It for instance that all important subjects have been a gives a completeness to the description of any particular specialists, so that students may have full CEE substance, whereas the other plan of describing the facts, the accuracy of the information offered to the of animal chemistry, under the headings of the tissues, matters in which they happen to be particu organs, and functions involves a certain amount of rested. The space at the disposal of the wriz** repetition and the facts relating to any one group, such limited that what they have to say is nos, 24 as the proteids and carbohydrates will be found dis- exhaustive, but it is sound as far as it goes, tributed in different chapters. Dr. Sheridan Lea's plan | rally 'presented with most praiseworthy som

:55. The present volume falls in no respect below rates the bed into two basins, rising perhaps 10 metres or more el of those which have preceded it. Among the above their general level. Not seldom the bed of a lake consists

of scientific articles are Prof. James Geikie, who / of a linear series, three to six in number, of shallow basins, so vith the triassic system and with volcanoes ; Prof.

that a contour line, drawn along the axis of the lake, undulates who expounds the principles of thermodynamics ;

up and down with an "amplitude” of from perhaps 3 to 5

metres. A rather long, blunt.ended oval is the prevalent form W. Philip, who writes of tubercle ; and Sir F.

of these lakes, but to this there are exceptions. So far as can be ell, who has a paper on water-supply.

ascertained the contours of the land above the water-line are

reproduced beneath it. For instance, under the steep slopes of · Young's Tour in Ireland (1776-79). Edited, The Mont du Chat the bed of the Lac de Bourget plunges Introduction and Notes, by A. W. Hutton. Two abruptly down to a depth of over 120 m. (its greatest depth (London : G. Bell and Sons, 1892.)

being about 145 m.). eprint will be of real service to all who study the

of the Jura lakes, the Lac de St. Point (848-95 m. above the on of economic conditions in Ireland, and much

sea) is rather more than 6 kilometres long, the general width

being rather less than one-tenth of this ; a considerable part of ight also to excite and maintain the interest of the

its floor is 30 to 35 metres deep, and its greatest depth is about | reader. Arthur Young, as every one knows, was

42 metres. It contains no less than 6 basins, parted by " cols" arkably accurate observer of such things as about half-a-dozen metres above their lowest parts. This lake its have opportunities of noting, and his book on | is on the course of the Doubs, and lies parallel with the general lis in its own way hardly less valuable than his strike of the Jura, i.e. from N.E. to S.W. The Lac de elebrated work on France. The work was first | Brenets on the same river, nearly 100 metres lower down, is a ed in 1780, in the course of which two English narrow, winding lake, roughly 150 metres wide and perhaps 8 or s and one Irish edition were issued. Since that | 9 times as long. At its upper end is a sharply projecting, rather has not until now been reprinted as a whole. Mr. | shallow bay, but the channel of the Doubs can be traced clearly has done his work as editor admirably, and a

through this, deepening gradually from 5 to nearly 27 metres and seful bibliography has been prepared by Mr. J. P.

the whole lake is evidently only an enlargement of ihe river.

The subalpine lakes are no less interesung, and their testimony on.

generally agrees with that summarised above. Want of space forbids us to mention more than the lake of Annecy. This is deepest (about 65 m.) in its northern and widest part (nearest to

the effluent). The sub-aqueous contours on the western side are LETTERS TO THE EDITOR.

interrupted, to within about 10 metres from the bottom of the lake, litor does not hold himself responsible for opinions ex.

by a prominence, just like a drowned hilly spur. The shallowest

soundings over this, near its northern (outer) part, are only ssed by his correspondents. Neither can he undertake

33 metres, and the ground falls rapidly down from 5 to 55 return, or to correspond with the writers of, rejected

metres. On its northern or “lee" side (assuming a glacier to nuscripts intended for this or any other part of NATURE.

have followed the course of the water) is a submerged valley notice is taken of anonymous communications. ]

over 40 metres deep. The Lake of Annecy exhibits another

very singular feature. Near its northern end the bed deepens Some Lake Basins in France,

very rapidly from 30 to 80 metres; this funnel-shaped cavity is w weeks since M. Delabecque, Ingénieur des Ponts et

less than 200 metres in diameter, and is probably a submerged es at Thonon, kindly presented me with a copy of a work

swallow hole. These notes may, it is hoped, suffice to indicate nder his superintendence and to a great extent executed

the importance of this work. The gratitude of students is due to elf,' to which I should be glad to call the attention of

M. Delabecque (or supplying them with a valuable group of facts, of physiography. M. Delabecque, commissioned by

the collection of which must have entailed great labour. These, nch Government, has made a series of soundings of ten

however, appear to me not to lend themselves very readily to the France, near the Alpine region, and this Atlas records

support of the glacial excavation hypothesis ; but to be more Its of his work. Contour-lines, in most cases 5 metres

savourable to ihat which regards the larger Alpine lakes as ndicate the forms of the lake basins ; the use of varying

mainly formed by movements of the earth's crust after the blue makes these more distinct. Chief among the lakes

erosion of the valleys in which they lie. T. G. BONNEY. d is the Léman, in the survey of which, as only one shore ch territory, the Swiss engineers have cooperated. A this on a reduced scale, and without colours, appeared

Dust Photographs.
Forel's book, “Le Lac Léman " (see NATURE, Nov. 3,
Next in importance come the lakes of Annecy and of

IN Mr. Crost's paper on “ Breath Figures," printed in :; the remainder are situated either in the French Jura or

| NATURE for December 22 of last year (pp. 187, 188) he states :margin of the outer limestone zone of the Alps, a little

“Two cases have been reported to me where blinds with emThe Rhone.

bossed letters have left a latcnt image on the window near iding the Lake of Geneva, which was noticed in the article

which they lay.” The statement is not quite clear as I do itioned, these lakes are especially interesting for their bear

not understand whether the letters were in contact with the he difficult problem of the origin of lake-basins. Except

glass or not. de Bourgei, none of these can be said to lie in a great

Perhaps it may be interesting to place on record an observa. in valley, or on the probable track of a great glacier. If

tion of my own, made a few years ago, which struck me at the eir basins have been excavated by glaciers, we might

time as curious, but which I have not been able to verify since. (pect the Alps and Jura to be “spattered" with lakes, for

At the stations of the District Railway there is a useful al con be made to exceprional circumstances : while if

arrangement by which passengers are informed of the destination lours of their beds present resemblances to those of the

of the next train. It consists of a shallow box with glass sides Alpine lakes, such as the Lake of Geneva, the same

into which by a mechanical contrivance boards are let down llon ought to apply in the main to both groups.

on which the names of the stations are painted in white letters out a reproduction of the charts it is impossible to give

on a blue ground. The board with the words : INNER CIRCLE' an a rough idea of the evidence which ihey afford, but

is most frequently exposed. At night the box is (or was) owing statements may be helpful. As a general rule the

illuminated obliquely on either side by a tolerably powerful lamp. eepen as they broaden, the deepest water being com.

One night I was waiting for the train at the Victoria Station. found in the widest part. If in the course of the lake

There was some dislocation in the service ; the destination of res markedly approach so as to form a kind of “narrow,"

the next train was uncertain and the box was empty. On rresponds with a submerged neck or “col," which sepa.

glancing at it somewhat sideways I was however astonished

to see the words INNER CIRCLE' on the glass side of the box las des Lacs Français, Ministère des Travaux Publics." No

in quite clear dark letters on a pale illuminated ground, I name appears on the sheets. but I am informed by M. | drew the attention of one of the platform officials to it. He que that the Atlas can be obtained at Georg's Library, Geneva. saw it with persect distinctness, and seemed to think he had

but

Tested

ASSE

minna

noticed it before. Of course when the apparatus is in full shining particulariy brightly, being obscured, except at a working order there is little opportunity for doing so.

able intervals, by driving mist and light clouds. The box
The only explanation I could think of was:-(i) that the light ever, was exceedingly well marked, and formed a sia
of the lamp had produced some molecular change in the paint beautiful object, stretching as it did completely across the
coating the notice board ; (ii) that this had affected differently western end of Loch Oich, glimmering against the can
the blue and the white paint ; (iii) that the same cause had set ground of the mountains, and sinking into the wate
up some differential electrical condition of the board and the southern shore of the loch. The general colour of the
glass ; (iv) that a bombardment of particles of the blue paint yellow deepening into orange, several of the pristranic
had taken place on to the glass to which they had adhered; and however, being intermittently visible, especially a tince 1
that (v) the particles so adhering, by dispersing the light, pro- on the upper side.
duced the effect of the pale illuminated ground while the spaces The Abbey, Fort-Augustus, N.B.
occupied by the letters being relatively clean stood out dark.
Royal Gardens, Kew,

W. T. THISELTON-DYER.
February 1.

OPTICAL CONTINUITY.
MR. W. B. Croft's paper on Breath-Figures in your issue of
December 22 reminded me of some curious impressions of

| KEENNESS of sight is measured by the ang=1

K monumental brasses which are to be seen on the walls of

tance apart of two dots when they can oals Canterbury Cathedral. When I saw these impressions a few distinguished as two, and do not become confused years ago, it occurred to me that they might have been produced | It is usually reckoned that the normal eye is just by mere contact, the brass plates having possibly been hung for just unable to distinguish points that lie one nisu many years against the walls, in secluded corners, at a time when degree asunder. Now, one minute of a degree the Reformers would not let them remain in their proper angle subtended by two points, separated by matrices on the church floor. I had forgotten the particulars of part of an inch, when they are viewed at the cl these figures, but Dr. Sheppard, of Canterbury, has kindly sent

reading distance of one foot from the eye. 11.1 me the following notes by favour of Canon Fremantle :-"A

row of fine dots touching one another, each as sa number of impressions of brasses are in tbe basement (which is open to the air) under Henry IV.'s chantry in the Cathedral. A

a bead of one 300th part of an inch in diam. very good impression is on the western column of the crypt of ar

arranged on the page of a book, they would appear Trinity Chapel. . . . On the walls appear the shapes of

ordinary reader to be an extremely fine and coc the effigies. Sometimes the stone is unstained all over the area

line. If the dots be replaced by short cross stod of the figure, and surrounded by a broad dark smudge: and | line would look broader, but its apparent continy sometimes the case is reversed, and the figure is the exact nega | not be affected. It is impossible to draw any tive of the former kind ; that is to say, the area of the figure is shall commend itself to the eye as possessing more indicated by an uniform dark tint, whilst the surrounding stone larity than the image of a succession of dots + is unstained.” Dr. Sheppard suggests that an exact pattern strokes, 300 to the inch, when viewed at the dish seems to have been made in paper and then fixed to the wall

a foot. Every design, however delicate, that can be whilst it was brushed over with linseed oil. But this does not

with a line of uniform thickness by the best machine account for the white effigies on a dark ground."

most consummate artis , admits of being mimickel I would commend these impressions to the notice of those interested in the subject. It may be that, though some were

coarsest chain, when it is viewed at such a disa made intentionally, others are the result of simple contact.

the angular length of each of its links shall not F. J. ALLEN.

one minute of a degree. One of the apparently a Mas in College, Birmingham, February 4.

outlines in nature is that of the horizon of the sea ordinary weather, although it is formed by waveli

slopes of débris down the sides of distant Fossil Plants as Tests of Climate.

appear to sweep in beautifully smooth curres, In continuation of my recent letter, permit me to call alten. reaching those mountains and climbing up the #1 tion to a communication on the bread fruit trees in North | path may be exceedingly rough. America, by Mr. F. H. Knowlton, of the National Museum, The members of an audience sit at such vark Washington, U.S., which appears in your American contem- tances from the lecture table and screen, that! porary Science for January 13. The forty living species of

possible to illustrate as well as is desirable, el Artocarpus are all confined to tropical Asia and the Malay

alay through which a row of dots appears to run it Archipelago. A. incisa, the true bread fruit tree, and one or

tinuous line, as the angular distance between the two others, are largely cultivated in the tropics. They are small or medium-sized trees with a milky juice, large leathery leaves,

lessened. I have, however, hung up chains acco and monacious flowers. The female flowers are long club

beads of various degrees of coarseness. Some shaped spikes, which uniting form one large mass known as the

will appear as pure lines to all the audience : “bread fruit,” the interior containing a pulp when ripe like new whose coarseness of structure is obvious to those bread.

nearest, will seem to be pure lines when viewed 1 The first fossil bread fruit was discovered in boulder county furthest seats. Colorado in late cretaceous rock, and was named by the late Prof. Although 300 dots to the inch are required to 31 Le ) Lesquereux Myrica (?) Lessigiana, other fragments he called idea of perfect continuity at the distance of cael Aralia pungens. The subsequent researches, or more perfect will shortly be seen that a much smaller numb| specimens of Dr. A. S. Nathorst, proved these to belong to one

to suggest it. species, Artocarpus Lessigiana. Dr. Nathorst is the discoverer

The cyclostyle, which is an instrument used for of another species closely allied to A, incisa, which he calls A. Dicksoni, which he obtained from the cretaceous flora of

writing, makes about 140 dots to the inch. Thes Waigatt, West Greenland, which the previous labours of Profs.

minute spur wheel or roller, instead of a point ; the Heer and Nordenskiöld bad shown to be of a tropical or sub

is made on stencil paper, whose surface is covered tropical character, containing as it does numerous species of brittle glaze. This is perforated by the teeth 0 1 ferns of the order Gleichenialeæ, and several species of cycas.

wheel wherever they press against it. The half per

CHAS. E. DE RANCE, sheet is then laid on writing paper, and an inked H.M. Geological Survey, Alderley Edge, Manchester. worked over the glaze. The ink passes througe

forations and soaks through them on to the paper

consequently the impression consists entirely of Lunar Rainbow in the Highlands.

irregular cross bars or dots.
This interesting phenomenon (a very unusual one in this
latitude) was observed near here on the morning of the 3rd inst.,

1 Extract from a lecture on The Jus:-Perceptible Different

before the Royal Institution on Friday, January 17, tuy F about six a.m. The moon was two days past full, and was not F.R.S.

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I exhibit on the screen a circular letter summoning a of equidistant points on the above principle, noting mmittee, that was written by the cyclostyle. The at the same time the bearing of each from its predecessor. iting seems beautifully regular when the circular is I thereby obtained a formula for the profile, consisting of otographically reduced; when it is enlarged, the dis 271 letters. Then I put aside the drawing, and set to atinuity of the strokes becomes conspicuous. Thus, work to reproduce it solely from the formula. I exhibit have enlarged the word the six times; the dots can the result; it is fairly successful. Emboldened by this en be easily seen and counted. There are 42 of them first trial, I made a more ambitious attempt, by dealing the long stroke of the letter h.

with the profile of a Greek girl copied from a gem. I was The appearance of the work done by the cyclostyle very desirous of learning how far the pure outline of the uld be greatly improved if a fault in its mechanism original admitted of being mimicked in this rough way. uld be removed, which causes it to run with very | The result is here ; a ring has been painted round each equal freedom in different directions. It leaves an ly, jagged mark wherever the direction of a line changes idenly. A much coarser representation of continuous lines is ven by embroidery and tapestry, and coarser still by ose obsolete school samplers which our ancestresses orked in their girlhood, with an average of about sixen stitched dots to each letter. Perhaps the coarsest ttering that is ever practically employed is used in erlorating the books of railway coupons so familiar to avellers. Ten or eleven holes are used for each figure.

A good test of the degree of approximation with which cyclostyle making 140 persorations to the inch is able to mulate continuous lines, is to use it for drawing outline ortraits. I asked the clerk who wrote the circular just xhibited to draw me a few profiles of different sizes, anging from the smallest scale on which the cyclostyle ould produce recognisable features, up to the scale at which it acted fairly well. Here are some specimens of the esult. The largest is a portrait of 15 inches in height, by which facial characteristics are fairly well conveyed; somevhat better than by the rude prints that appear occasionally n the daily papers. It is formed by 366 dots. A medium ize is 1 inch high and contains 177 dots, and would be olerable if it were not for the jagged strokes already spoken of. The smallest sizes are } inch high and contain about ninety dots; they are barely passable, on account of the jagged flaws, even for the rudest portraiture.

I made experiments under fairer conditions than those of the cyclostyle, to learn how many dots, discs, or rings dot in order to make its position clearly seen, without per inch were really needed to produce a satisfactory | obliterating it. The reproduction has been photographicdrawing, and also to discover how far the centres of the ally reduced to various different sizes. That which contains dots or discs might deviate from a strictly smooth curve only fifty dots to the inch, which is consequently six times without ceasing to produce the effect of a flowing line. It as coarse as the theoretical 300 to an inch, is a very must be recollected that the eye can perceive nothing creditable production. Many persons to whom this portrait fiper than a minute blurr of one three-hundredth has been shown failed to notice the difference between it part of an inch in angular diameter. If we repre and an ordinary woodcut. The medium size, and much sent a succession of such blurs by a chain of discs, more the smallest size, would deceive anybody who viewed it will be easily recognised that a small want of them at the distance of one foot. The protractor used in exactitude in the alignments of the successive discs must making them was a square card with a piece cut out of be unimportant. If one of them is pushed upwards a its middle, over which transparent tracing paper was trifle and another downwards, so large a part of their pasted. A small hole of about of an inch in diameter respective areas still remain in line, that when the several was punched out of the centre of the tracing paper ; discs become of only just perceptible magnitude, the pro sixteen minute holes just large enough to allow the entry jecting portion will be wholly invisible. When the discs of the sharp point of a hard lead-pencil were perare so large as to be plainly perceptible, the alignment forated through the tracing paper in a circle round the has to be proportionately more exact. After a few trials centre of the hole at a radius of 1 inch. They correIt seemed that if the bearing of the centre of each disc sponded to the 16 principal points of the compass, from that of its predecessor which touched it, was and had their appropriate letters written by their sides. correctly given to the nearest of the 16 principal The outline to be formulated was fixed to a drawing-board, points of the compass, N., NNE., NE., &c., it was fairly with a T rule laid across it as a guide to the eye in keepsufficient. Consequently a simple record of the succes ing the protractor always parallel to itself. The centre sive bearings of each of a series of small equidistant steps of the small hole was then brought over the beginning of is enough to define a curve.

the outline, and a dot was made with the pencil through The briefest way of writing down these bearings, is to the perforation nearest to the further course of the outassign a separate letter of the alphabet to each of tbem, line, and this became the next point of departure. While a for north (the top of the paper counting as north), b for | moving the protractor from the old point to the new one north-north-east, c for north-east, and so on in order up it was stopped on the way, in order that the letter for the top. This makes e represent east, i south, and m west. bearing might be written through the central hole.

To test the efficiency of the plan, I enlarged one of the A clear distinction must be made between the proposed Cyclostyle profiles, and making a small protractor with a plan and that of recording the angle made by each step piece of tracing paper, rapidly laid down a series from the preceding one. In the latter case, any error of

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