;oo 



NATURE 



[March 22, 1894 



system already adopted by Dr. Common, viz. the flotation of 

 the polar axis of the telescope. This is done by making a tube 

 for the Newtonian reflecting telescope (which is necessarily 

 closed at the lower end) of such a weight, and with its weight 

 ^o distributed that it will not only float in water at a certain 

 point (preferably near the upper end), but will be in a state of 

 equilibrium when placed at any position down to a certain 

 angle, say to within 20° of the horizon, the angle depending on 

 the exact outside form of the tube. With a pair of trunnions 

 attached at the water-line, an 8o-ton telescope could be mounted 

 and earned by an equatorial without throwing any weight what- 

 ever on that equatorial, the force necessary to drive the instru- 

 ment being dependent only on the friction to be overcome in 

 carrying the tube at an exceedingly slow rate through the water. 



Paris, 



Academy of Sciences, March 12. — M. Lcewy in the chair. 

 — Observations of the new planet BB (Charlois), made at the 

 Paris Observatory, by MM. O. Callandreau and G. Bigourdan. 

 — Preparation and properties of boron carbide, by M. Henri 

 Moissan. Several methods are given for the preparation of this 

 compound at the high temperatures of the electric arc. Clearly- 

 defined crystals of CBg are obtained by heating the requisite 

 quantities of carbon and boron with about twice their weight of 

 copper in the electric furnace for six or seven minutes. After solu- 

 tion of the copper and extraction of a little graphite, the residue 

 has a density of 2"5i, and is hard enough to polish diamond. 

 The properties of this compound are given at length. — On the 

 reproductive organs of Ancylus fltiviatilis, by M. de Lacaze- 

 Duthiers. — On the internal pressure of fluids and the form of 

 the function (p{pvt) = O, by M. E. H. Amagat. The author 

 takes the general form {p -f tt) {v - a) = RT, hence deve- 

 lops the formula (p + T^ - p\{v - a) = RT, in which 



■dp 

 dt 



(v - a) = R, whence the values of a for a series of volumes 



are calculated. These values may be represented by the ex- 

 pression a- — a -{- B (v - a)" where B = o'oojy, n = 1, 

 and o = o'ooo4. But, from the variation of ir (the internal 



pressure) with the volume, we have tt = A ^^-^ * ; for hydrogen 



■V'" 



A = o 000506, w = 3, and e = o'ooaiii. With these values 

 of the arbitrary constants the formula 



(/ + A^^) {v~[a + B(v- a)"-]) = RT 



gives for hydrogen values for the pressure calculated from the 

 volume agreeing well with the actual pressures from 100 to 

 2800 atmospheres. The calculated interior pressure for unit 

 volume at zerotemperature and normal pressure is o 000875 atmos. 

 Kelvin and Joule's experiments make the value 00008 atmos. 

 — Magnetic observations in Madagascar in 1892, by P. E. Colin. 

 — On the presence of a polymorphous microbe in syphilis, by 

 Dr. Golasz. The author gives evidence of the existence in the 

 blood of syphilitic patients of a polymorphous bacillus belonging 

 to a species nearly related to Leptothrix and Cladothrix, and 

 hence similar to the species found in cases of tuberculosis, 

 leprosy, and glanders. — On the triangle of sequences. An ab- 

 stract of a memoir by M. Desire Andre. — Observations of the 

 new planets AX (Wolf, March i) and AZ (Courtv, March 5) 

 made at Lyons Observatory, by M. G. Le Cadet. — Observation 

 of the planet 1894 AZ, made with the great equatorial of the 

 Bordeaux Observatory, by M. L. Picart. — Observations of 

 planets, made at the Toulouse Observatory (Brunner equatorial), 

 by M. F. Ro-sard. — Solar phenomena observed during the third 

 and fourth quarters of 1893, at the observatory of the Roman 

 College. A letter from M. P. Tacchini.— On the capillary de- 

 pression of the barometer, by M. C. Maltezos. A mathematical 

 investigation resulting in the expression of the opinion that the 

 practical comparison method must still be relied on for correct- 

 ing barometric heights for capillarity.— Achromatism and 

 chromatism of interference fringes, by M. J. Mace' de Lepinay. 

 —Use of electricity for following the phases of certain chemical 

 reactions, by M. Jules Gamier.— A contribution to the study 

 of ferments, by MM. P. Hautefeuille and A. Perrey.— On the 

 spark spectra of some minerals, by M. A. de Gramont. The 

 nrimeral sulphides, selenides, and tellurides, and native gold, 

 silver, copper, bismuth, arsenic, and antimony have been 

 studied.— Influence of time on the absorption of carbon 

 NO. 1273, VOL. 49] 



monoxide by the blood, by M. N. Grehant. — On the prostatic 

 utriculus and the vasa deferentia in the cetacse, by MM. H. 

 Beauregard and R. Boulart. — On composite ascidians of the 

 genus Distaplia, by AL Caullery. — On ears of maize attacked by 

 Alucite des cereales in Central France, by M. A. Laboulbene. — 

 Influence of potassium salts on nitrification, by MM. J. Dumont 

 and J. Crochetelle. — On the fertility of the giant Persi- 

 caire {Polygonum sachalinense), by M. Ch. Baltet. — Physio- 

 logical researches on fungi, by M. Pierre Lesage. — On the fossil 

 Cedroxylon varolense. A note by MM. B. Renault and A. 

 Roche. — On the variation of the composition of the water of 

 lakes with the depth and according to the seasons, by M. A. 

 Delebecque. — On the temperature of caverns, by M. E. A. 

 M artel. 



BOOKS, PAMPHLETS, and SERIALS RECEIVED, 



Books. — Statesman's Year-Bnok, 1894 (Macmillan). — A Handbook of 

 Gold-Milling : H. Louis (Macmillan). — The Handbook of Jamaica for 

 1S94 (Stanford). — Ueber die Spectren der Elemente : H. Kayser and C. 

 Runge (Berlin, Reimer). — Deutsche Uebersef ische Meteorologische Beo- 

 bachtungen, Heft vi. (Berlin). — Construction et Resistance des Machines a 

 Vapeur ; Alheilig (Paris, Gauthier-Villars). — Machines Frigorifiques a Air : 

 R. E. de Marchena (Paris, Gauthier-Villars). — Popular Lectures and Ad- 

 dresses : Lord Kelvin, Vol. 2, Geology and General Physics (Macmillan). — 

 A Treatise on Hydrostatics: Prof. A. G Greenhill (Macmillan). — Methods 

 of Pathological Histology : Prof. C. von Kahlden, translated and edited by 

 Dr. H. M. Hetcher (Macmillan). 



Pamphlets. — Return of Mineral Production in India for 1892 (Simla). — 

 River Temperature, Part i : H. B. Guppy. — The Aerial Oxidation of Ter- 

 penes and Essential Oils : C. T. Kingzett. — Quelques Conclusions et Appli- 

 cations de I'Anthropologie (Paris, Masson). 



Serials. — Bulletin of the Natural History Society of New Brunswick, 

 No. II (St. John. N.B). —Journal of the Chemical Society, March (Gurney 

 and Jackson). Insect Life. Vol. 6, No. 3 (Washington). — Rendi'-onto dell' 

 Accademia delle Scienze Fisiche e Matematiche, serie 2^., Vol. 8, fasc. 1°, 

 e 2° (Napoli). — Economic Journal, March (Macmillan) — J urnal of the 

 Institution of Electrical Engineers, No. loq. Vol. xxiii. (Spon) — American 

 Naturalist, March (Philadelphia). — Royal Natural History, Vol i. Part 5 

 (Warne). — Proceedings of the Indiana Academy of Sciences, 1892 (Brook- 

 ville, Ind.). 



CONTENTS. PAGE 



Theory of Functions. By G. Ch 477 



The Construction of Drum Armatures and Commu- 

 tators. By E. Wilson 478 



British Mosses. By E. F 479 



Our Book Shelf:— 



Eleanor A. Ormerod : " Report of Observations of 

 Injurious Insects and Common Farm Pests, during 

 the Year 1893, with Methods of Prevention and 



Remedy."— W. F. K 480 



Macfarlane : " On the Definitions of the Trigono- 

 metric Functions " 480 



Carr: "Key to Mr. J. B. Lock's Shilling Arith- 

 metic " 480 



Letters to the Editor : — 



The Thermal Expansion of Diamond. ( With Z>z'a- 



o-raw.)— Dr. J. Joly, F.R.S 480 



The North-East Wind.— S. H. Burbury, F.R. S. . 481 

 The Suspension of Foreign Bodies from S piders' 



Webs.— R. Philipp 481 



The Falls of Niagara and its Water-Power. {Illus- 

 trated.) 482 



Notes 486 



Our Astronomical Column : — 



Comet Spectra as affected by Width of Slit 489 



The Astigmatism of Rowland's Concave Gratings . . 489 



The Institution of Naval Architects 490 



Cholera. By Dr. E. Klein, F.R.S 492 



Geological Survey of the United Kingdom. I. By 



Sir Archibald Geikie, F.R.S 495 



University and Educational Intelligence 497 



Scientific Serials 497 



Societies and Academies 498 



Books, Pamphlets, and Serials Received 500 



