1 66 



NA TURE 



[Dec. 31, 1874 



vrlume, hon-evcr, as this, wc have the matcrinl out of 

 which the chemist of the future will elaborate his general 

 theory of chemical action ; and not only this, but we 

 have a storehouse from which the student of our science 

 may draw rich supplies of knowledge, and to which he 

 may always refer, well assured that he will not be sent 

 away empty. 



The arrangement of the new Handivorlcihuch is very 

 similar to our own " Watts' Dictionary." Amid the variety 

 and excellence of the articles, it is difficult to choose any 

 for special mention. 



The articles on Equivalents and Atoms are especially 

 to be commended, the former by Prof. Kekul^, the latter 

 by Prof. Fittig. In the former article the author defines 

 the correct and true meaning of the word "equivalent" ; he 

 shows how vague oftentimes are the grounds upon which 

 we pronounce that such a substance is equivalent to such 

 another, and he clearly points out the great advantages 

 possessed by the modern atomic notation as compared 

 with the old and vague so-called equivalent notation. 



In the article on Atoms we have a clear and succinct 

 account of the modern chemical theory, and an interpre- 

 tation of the way in which the older ideas of equivalency 

 are applied to the newer atomic doctrines. 



The articles on Analysis are generally full and satis- 

 factory. It is strange, however, that such an excellent 

 method of qualitative testing as that preserrtcd by 

 " Bunsen's Flame Reactions " should be overlooked. 



There are excellent monographs on Aniline and Benzol, 

 by Prof Hofmann and Zincke respectively; while on such 

 subjects as tlie Respiration of Animals and Plants, and 

 Zoo-chemistry in general, we have articles from the pen of 

 I'inf. V. Gorup-Besanez. The woodcuts are admirable ; 

 n ihis respect the German vvoik is far ahead of our 

 i n^lish Dictionary. Let us hope that the work will be 

 completed as promised in the prospecius, and that the 

 volume alicady published will not add another to the 

 already too long list of great German scientific works tho 

 opening volumes of which stand waiting for their suc- 

 cessors, but seemingly waiting in vain. 



M. M. Pattison Muir 



OUR BOOK SHELF 



Die fossilcn Bryo~oen dcs osicrrcichiscli-nngarischcn 

 Miviiiiis. Von Pi of. Dr. A. E. Ritter von Reuss. I. 

 Abtheilung. Pp. 50. 4to. (Wien : 1S74.) 

 Ccoloi^isiher Ban dcr Inscl Sainothrakc. Von Rudolf 



Hoernes. Pp. 12. 4to. (Wien: 1874) 

 These publications are extracted from the Transactions 

 of the Imperial Academy of Sciences. Dr. v. Reuss's 

 paper describes the Salicornaridre, Cellularidne, and 

 iVlembraniporid;e, a number of the species being new ; 

 andgivss twelve excellent plates of the fossils. Accor- 

 ding to Herr Hoernes, the island of .Samothriki consists 

 of abrupt hill-masses of ancient crystalline rocks, such as 

 granite, clay-slate, hornblende rock, &c., overla d, espe- 

 cially in the northwest and north, with deposits of Eocene 

 age, and diluvial and recent accumulations. A coloured 

 sketch-map accompanies the paper. 



Uber die palacoznisclien Gebilde Podidiens mid denn 

 Vcrsteincnint^efi. Von Dr. Alois v. Alth. Erste Ab- 

 theilung. Pp..78. (Wien: 1874.) 



Uber die triadisehen Pelecypoden-Galtiiiigeti, '■' Daonella '' 

 intd^^ llalobia." Von Dr. E. Mojsisovics v. Mojsvdr. 

 Pp. 38. (Wien : 1874.) 



Both these publications are issued by the Austro-Hun- 



garinn Geological Survey, being extracted from the 

 " Abhandlungen, Band vii." This mode of republishing 

 in a separate form the papers contributed to their Trans- 

 actions cannot be too strongly commended. Dr. A. v. 

 Alth's paper relates to the region which lies between the 

 rivers Bug and Dnieper. It is illustrated by five litho- 

 graphic plates of fossils, a number of which are new 

 species of Pteraspis, Scaphaspis, Cyathaspis, Beyrichia, 

 &c. Dr. Mojsisovics' paper is also illubtrated by five 

 lithographic plates of a number of new species of the 

 genera Daonella and Halobia, which are described and 

 named by himself. 



LETTERS TO THE EDITOR 



[ The ndltor does not hold himself responsible fo?- opinions expressed 

 by /lis correspondents. Neither can he undertake to return^ 

 or to correspond ivitli the writers of, refected manuscripts. 

 No notice is talcen of anonymous communications.'\ 



On the Inventor of Clock Movement applied to 

 Equatorials. — Suum Quique 



In a pamphlet by Col. LausseJ.it, "On the Horizontal Astro- 

 nomical Telescope," in which he claims for himself the inven- 

 tion of applying a heliostat to direct the light of any object into 

 a fixed telescope, I find at p. 2 this statement in speaking of the 

 equatorial : " The idea of so endowing a telescope with a moving 

 power which annuls, or, to speak more exactly, compensates the 

 motion of the earth, is due to a Frer.ch watchmaker of the last 

 century, named Passemont." 



I am sure the distinguished wri'er would net knowingly have 

 done to another the injustice of which in his own case he com- 

 plains ; but in I'act this invention belongs to a much earlier date, 

 and to one of far greater fame, the il ustrious Robert Houke, 

 who describes it, with a figure, in his " .Animadversions on the 

 Machina Coelestis of Heveius " (my copy bears dale 1674). It 

 was primarily intended to facilitate the pro.c-s of measuring 

 directly the distance of two stars, a process which was then much 

 in vogi e, but which must have been very troublesome from the 

 difiiculty of following ihem. It consists of a strong polar axis, 

 adjusted at its lower bearing by screws, and canyuig at t0(i a 

 cross arm, one end of which bears a counterpoise, and the other 

 a quadrant or fcxtant w th a ball-and-socket sup,_'ort, by whieh 

 its plane can be made to coincide with that pass ng ihruugh t-»o 

 stars. But Hooke expi-essly stated iliat a telescope may be 

 similarly atl.iched there. The polar axis carries jn octant whose 

 limb is ratchcd. and driven by a screw coiintcted with a clock. 

 The clock is regulated by a conicil pendulum ; and he describes 

 the mode of altering it- rate for the sun, moon, and planets. Of 

 the date or details of M. Passemont's re-invention thtre is no 

 trace in L.alande. Hut, as I find jn Rees' Cyclopa-dia (art. 

 " Passemont ") that he was born in 1702, and that his first pub- 

 lication appeared in 1738, it is by at least half a century later 

 than Hool:e's. 



It also deserves notice that Col. I^aussedat's inven'ion is de- 

 scribed by Hool.e in his treatise on Ileli :scopes two years later 

 (1C76). His word- .are : " I explained at the same time to the 

 Royal .Society several other ways of facilitating the use of very 

 long g'asses for other objects in the heavens (he had been speak- 

 ing 01 the am) by the help of one tellecting plae on^y, and that 

 w.^s by a tube fixed either perpendicularly, horizontally, or ob- 

 liquely ; for it mittered not, wh ther as to ihe .seeing the object 

 in .Tny pirl of the heaven, and the object could be as easily found 

 as l)y the c immon telescope of ihe same length. But of these 

 elsewhere." 



I have not, however, been able to find any fur. her notice of it 

 in t is works. 



This invention leads me to a sug >estion which may be interest- 

 ing to astronomers. The Royal .Society possesses two Huyghc- 

 nian object-glasses, one of 120 feet focal length, the other of 

 200. Some years ago a question wasiaiel by l\f. O. Struve as 

 to the defining power of the first-named of these, in reference to 

 a discussion on the rings of Saturn, and the Society appointed a 

 committee to examine. It was tried at the Kew Observatory, 

 and defined a watch-dial as well as a good 3"75"'n^h achromatic. 

 Tlii^ was considered sufficient without incurring thegrcat expense 

 of such a scaflolding or building as would have been required to 

 use it for celestial observations. These, however, can be easily 

 managed by Col. Laussedat's arrangement. If successful, these 



