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Now Ready, price 9s.6d, strongly bound.

CASSELL'S FRENCH AND ENGLISH DICTIONARY: * r drawing Laudats, etc; from the English Dictionaries of Ogilvie, Johnson,

Webster, Composed from the French Dietionaries of the French Academy, Bescherelle, ute; and trom the Technological and Scientific Dictionaries of both Lan.

Kures By Professors Ds LOLNE and Wallace, and HENRY BRIDGEgalvasia

NAX, Esq.

The following are the distinctive features which render this work superior to any of the same class now extant. It has been compiled with unusual var tro the very best authorities. It contains correct renderings of all the valutera words and phrases—including those of science, ari, manufacSurs ponuere, law, politics, etc., as well as familiar conversation - which Audapensable to a knowledge of language, but yet are rartly, if ever, to e focad properly translated in any Dictionary: The idiomatic usages of Le tue languages-the constructions of verbs, the force of prepositions, and fe changes of meaning caused by different combinations of words-are we copiously and carefully illustrated than elsewhere witbin the same

The meanings are also classified and arranged in such a manner as ou prevout the possibility of mistake. To crown all, the work is as moderate Herve as it is comprehensive in aim, accurate in detail, and superior in are suge moul The French-English Division, price 4s. paper covers, or 5.8. Amwa; the Auglish-French Division, price 4s. paper covers, or 58.

CAR LESSONS IN FRENCH. Parts I. and 11.-By Professor Fas****** tree each in paper covers, or 23. 6d. bound in cloth. The Paw Parts in One Volume, price 4s. 6d.

APV Cassell's Lessons in French, containing Translations of all the Time Price Is. paper covers, or ls. 6d. cloth. HRNETS HANTAL OF THR FRENCH LANGUAGE.-By Professor De

Preos neatly boaad.

ar lesers in Frencu, og an entirely Novel and Simple Plan.

Rame forma trom The Working Man's Friend." Price 6d., veteneenpies of this work have been sold.



Aint glass this difference is 0:0433; in crown glass, 0.0246 ; ON PHYSICS, OR NATURAL PHILOSOPHY. the dispersion of the fint being thus nearly double that of the No. XLIX.

In prisms of the same substance, the dispersion

decreases with the refracting angle of the prism; for if this (Continued from page 334.)

angle were reduced to nothing, the surfaces of incidence and

emergence would be parallel, and the light would not be DISPERSION AND ACHROMATISM.

decomposed DECOMPOSITION OF WHITE LIGHT-THE SPECTRUM. colours than those which present themselves in the solar

In spectra produced by artificial light, we observe no other The phenomenon of refraction is not so simple as is generally spectrum, but in general some are wanting. Their relative supposed. When white light, or that which arrives from the intensity is also much modified. The hue which prevails in sun, passes from one medium to another, it not merely deviates artificial light prevails equally in its spectrum. Yellow, red, in its course; it is decomposed into several species of lights,-a and green flames give spectra, in which the dominant tint is phenomenon which is designated dispersion. To demonstrate yellow, red, or green. that white light is decomposed by refraction, let us admit

In order to produce a solar spectrum, in which the seven into a dark room a sunbeam & A, through a very small opening principal colours shall be sufficiently distinct, the opening by in the shutter, fig. 302. This beam would form at k an image diameter, and the angle of refraction in the prism being 60°;

which the sunlight enters should be only about an inch in
Fig. 302.

the screen on which the spectrum is received should be distant
five or six yards.

The Colours of the Spectrum are simple and unequally refrangible.
-If we isolate one of the colours of the spectrum, intercepting
the others by means of the screen E, as shown in fig. 303, and

Fig. 303.



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cause it to pass through a reduced prism B, we observe still a of the sun, round and colourless ; but if we interpose a prism deviation, but the light remains identically the same; that is, of flint glass P, disposed horizontally, the beam on entering the image received on the screen n, is red, if a red beam passes and issuing from the prism is refracted towards its base ; and through; and so of blue, and the other colours. This demoninstead of an image round and colourless, we receive on a strates that the colours of the spectrum are simple, or not distant screen an image 1 H, which in the horizontal direc- decomposable by the prism. tion is of the same dimension as the original beam ; but if Moreover, colours are unequally refrangible, which means

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vertical, it is oblong, and coloured with all the beautiful tints that they possess different indices of refraction. The elongated of the rainbow. This coloured image

is called the Solar spectrum. form of the spectrum will suffice to exhibit the unequal There are in reality in the spectrum an infinity of tints ; but refrangibility of simple colours ; for it is evident that the We distinguish seven principal colours, in the following order, violet colour, which deviates most towards

the base of the beginning with the most refrangible : 'violet, indigo, blue, green, prism, fig. 302, is also the most refrangible, and that the red yellowo, orange, red. These colours do not all occupy an equal colour, which deviates least, is the least refrangible. But we space in the spectrum ; the violet has the most, and the orange can demonstrate the unequal refrangibility of simple colours

by several experiments. We shall take the two following: With transparent prisms of different substances, or with 1st. Let us affix to a piece of black pasteboard two narrow prisms of thick glass filled with various liquids, we obtain slips of paper, the first red, and the second violet, and then spectra formed of the same colour and in the same order ; but look at them through a prism. We shall see that both become the angle of refraction being equal, the length of the spectrum deviated, but unequally, the red slip less than the violet, Faries with the substance of which the prisin is composed. which proves that red rays are less refrangible. Those which reach the greatest extent are called more disper- 2nd. We can, again, make Newton's experiment of crossed site, and the dispersion is measured by the difference of the prisms. On the first prism A, fig. 304, disposed horizontelly, we indices of refraction in the extreme rays of the spectrum. In admit

a zencil of white light s, which,

when it has only traver



paysans ?

non ?

6. Que fait la famille noyée de 14. Que dit-il de l'amour du W. MARTIN (New Swindon); PETER ALEXANDER (Glasgow); A. Laid. larmes ?

LAW (North-bank); GEORGE WILD (Dalton-on-Tees); and 'J. RUSSELL peuple pour l'archevêque ?

(Chislehurst), have solved most of the first portion of the second Centenary 7. Que dit le bon archevêque? | 15. Comment lui propose-t-il of Algebraical Problems. Isak has also solved them remarkably well in 8. Que dit-il à l'égard de Bru.

de faire le voyage ?

general, but he is wrong in No.29, though he has arrived at the given answer, non ?

16. La nouvelle de son arrivée wbichebould have been, as several of the above students have pointed out, 9. Quelle fut la réponse des se répandit-elle ?

JOHN W. JACKSON (Dublin): To divide unity into extreme and mean 17. Que forma-t-on alors ? ratio, let z be the greater part, and y the less. Then by definition we havo 10. Que dit-on ensuite à Bru. 18. De quoi couvrit-on la ci-* + y:*::*? y, and by supposition : + y = 1, by solving which equations

vière ?

V y will be found =

IN5–1. 11. Comment Brunon reçoit - | 19. Que fit le bon prelat?

whence y, and consequently 7, may

2 elle les caresses de la famille? | 20. Que fait tout le hameau ?

be obtained. The same method may be applicable whatever number be used 12. Que dit alors Fénelon? 21. Comment le cortège était-il instead of unity. 13. Que lui répond le villa- éclairé ?

To find the greatest common measure of
22. Où les paysans portèrent-
ils Fénelon:

15 a5 + 10 at 6 + 4 a3 b2 + 6 al 13 – 3 a bk

and 12 a3b2 + 38 a b3 + 16 a b -- 10 65. Striking out the facNOTES AND REFERENCES.-a. from accourir; L. part ii., tors in each which are not common to both, we have as follows: p. 76.-_b. from croire ; L. part ii., p. 84.--c. L. S. 41, R. 6 - 6a3 + 19a2b+8 ab? 563)15 at +10 ab + 4 a-b2 +6 a63--364 d. que n'ai-je pu voler! Ok? that I had had wings ! literally,

2 that I could have flown !-e. la here relates to peine.---f. L. S. 72, R. 1.-9. from abattre; L. part ii., p. 76.--h. en dais, as a 30 a' + 20 a76 +8 a8 +12,963 – 664/5 a canopy.--., ;. L. part ii., $ 49, R. (2.)

30 a + 95 a+b+ 40 a2b? — 25 ab3

gvois ?


b) - 75 236 — 32 a-b2 + 37 ab3 - 64 ANSWERS TO CORRESPONDENTS.

- 75 a3 -- 32a2b + 37 ab? — 6 63

2 J. W. H. F. (Spalding): It would b: unbecoming in the publisher to adopt his suggestion, however grateful he might feel for the kindness evinced.-W. JARDINE (Glasgow): Persevere, your next attempt will be - 150 m - 64 a2b + 74 ab? 1253

-25 better.- USTALOGA (Okehampton): Cassell's Latin Dictionary, edited by Dr. Beard, will be completed in about a month, price 9s. The first part is

- 150 a3-475 a+b — 200 ab- + 125631 now ready, price 53. cloth, or 48. paper covers.-A. EDWARDS (London): Greek was at that period generally understood by the Jews, and much more 137 b) 411 a·b +274 ab? - 137 63 extensively spoken than Hebrew; whence the reason is obvious why the books of the N, T, were written in Greek: any second-hand bookseller will supply a cheap copy of Rollin : Latin Dictionaries may be had cheap; but

3 a2 + 2 ab--02) 6 a3 + 19 a 23 +8 ab56% the best, and consequently the cheapest, is Cassell's, edited by Dr. Beard;

ab 2 ab the Biographies will follow in their turn. The others ought not to require an answer for so intelligent a correspondent.-R. H. (Southampton Buildings): Latin and Greek.-8. EMBLETON (Blyth): His case is that of

15 a+b + 10 ab? 563 thousands, by means of the POPULAR EDUCATOR.-E. J. BREMNER (Carlisle): More information acceptable.-J. A. (Gateshead): The last and

15 ab + 10 ab? - 563 best French Dictionary is Cassell's, edited by Professors De Lolme and Wallace, and H. Bridgeman, Eeq.: price 9s. 6.-DIXON (Hull): Write to whence we see that 3 a2 + 2 ab - b2 is the greatest common J. Petheram, Bookseller, High Holborn: the German Pronunciation Lessons are extremely simple, and easily mastered.-A. ROBINSON (Halifax): Leara measure required. the rules of perspective by all means.

SIMPSONIUS: Frenchmen generally sound the s in Gil Blas.-BETH (York); An axlom is a self-evident proposition, a postulate is a proposition the truth of which is asked to be granted for the sake of argument. The former is derived from the Greek word afiwja, which comes from a fiów, to think fit; and the latter from the Latin postulatum, the past participle of postulare, to ask or demand, so that it properly means a thing asked.

We can

LITERARY NOTICES. not with propriety answer the other questions.

R. Causer should consult our Lessons in English, where he will find specimens of parsing suitable for his guidance.

Now Ready, price 9s.6d. strongly bound. W. COTCHEIFER is correct in his solutions, but not so neat as he might be.

We have been asked for a solution of Problem 39 in the Second Centenary CASSELL'S FRENCH AND ENGLISH DICTIONARY: of Algebraical Problems. "By the question, a =is the quantity of wine after the first drawing Landais, etc.; from the English Dictionaries of Ogilvie, Johnson, Webster

Composed from the French Dictionaries of the French Acaderay, Bescherelle, off.' When the vessel has been filled up with water for the first time, as there are a-6 gallons of wine in a gallons of the mixture, there will be etc.; and from the Technological and Scientific Dictionaries of both Lafie a-6

(a-b) b

guages. By Professors De LOLME and WALLACE, and HENRY BRIDGIparts of a gallon in one gallon of the mixture, and

gallons in MAN, Esq.

The following are the distinctive features which render this work superior b gallons of the mixture.

to any of the

same class now extant. It has been compiled with unusual (a-bb (a-6) Hence a--

care from the very best authorities. It contains

correct renderings of all the la the number of gallons of wine left most modern words and phrases-including those of science, art, manufac: after the second drawing off. When the vessel has been filled up a second

ture, commerce, law, politics, etc., as well as familiar conversation which

are indispensable to a knowledge of language, but yet are rarely, if ever, te (a - )

be found properly translated in any Dictionary: The Idiomatic vagen of time, there will be, by similar reasoning to the above,

gallons the two languages-the constructions of verbs, the force of prepositions, and

the changes of meaning caused by different combinations of words of wine in ó gallons of the mixture. Therefore the quantity of wine in the

more coptously and carefully illustrated than elsewhere within the eas' (a - b)? (a -- b)' b

limits. The meanings are also el mixture after the third drawing off will be

to prevent the possibility of n

1 and arranged in such a mabao la price as it is comprehen

- nown all, the work is an ibor

rate in detail, and gaps (a - b) 3

arrangement. The Frenet. » gallons. And by a continuation of the same method, it may be neat cloth; the English:

· price ##. paper cox27" strongly bound.

rlee da. paper cosuprot shown that the quantity of wine remaining aller n such operations will be


1. and 11.-B, 1: (a-6)*

QUELLB. Price 2s. ex
We have put oursolution in a less concise and symmetrical form than Two Parts bound in 0

28.6d. bound 16 might have been adopted, that we night render it the more simple and

A KEY TO CASSET, the Exercises. Prie

.. containing intelligible.

JOHN Pogson deserves great credit for bis "general demonstration of A COMPLETE M
the cis different cases of the 17th Proposition of ihe first book of Eua!
bat he is not correct in speaking of the adjacent angles on the sap
a line as equal to two right angles, and hence inferring that txt"
lines are in vu« ayd llaw sume straigl.t line,



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