?oo 



NA TURE 



[July 29, 1897 



articles by Dr. D. E. Brinton, entitled "The Pillars of Ben" 

 and "The So-called ' Bow- Puller,'" besides brief notes on 

 collections and publications. 



The following are among the papers and other publications 

 which have come under our notice during the past few days : — 

 " Life in Sewers," by Mr. H. A. Roechling, in the Transactions 

 of the Leicester Literary and Philosophical Society (vol. iv. part 

 iii., 1897). The paper is an instructive account of bacterial 

 life found in the sewage itself and in sewer air, and the diseases 

 produced by it. — A paper on the distribution and migration of 

 Colorado birds, by Mr. W. W. Cooke, is published as Bulletin 

 No. 37 of the State Agricultural College, Fort Collins, Colorado. 

 The total number of species and varieties of birds which 

 occur in Colorado is 360, of which 228 are known to breed. 

 This is said to be a larger number of species than has been 

 taken in any State east of the Mississippi, and is only exceeded 

 by Nebraska with nearly four hundred species. — The tidal 

 phenomena of the St. John River, New Brunswick, Canada, at 

 low summer level, are described by Mr. A. Wilmer Duff in the 

 Bulletin of the Natural History Society of New Brunswick 

 (No. XV., 1897.) Dr. G. F. Matthew contributes to the same 

 bulletin a long review of the scientific work of Dr. Abraham 

 Gesner, the geologist. — The Pasteur Memorial Lecture delivered 

 by Prof. Percy Frankland before the Chemical Society on 

 March 25, and reported in Nature at the time (vol. Iv. 

 p. 518), is printed in full in the ]\x\-j Journal of the Society, 

 with an excellent portrait of Pasteur. 



The additions to the Zoological Society's Gardens during the 

 past week include a Chacma Baboon {Cynocephalus porcarius) 

 from South Africa, presented by Mr. W. H. Slather ; a Brown 

 Capuchin ( Cebus fatuellus) from South America, presented by 

 Mr. D. Mackintosh ; a Harnessed Antelope ( Tragelaphus 

 scriptus, (J ) from West Africa, presented by Mr. R. B. Llewelyn, 

 C.M.G. : a Vulpine Squirrel {Sciurus vulpintis) from North 

 America, presented by Messrs. A. G. and R. Rawlins ; a King 

 Parrot {Aprosniictus syanopygius) from Australia, presented by 

 Mrs. R. L. Turner ; a Crowned Horned Lizard {Phrynosotna 

 coronatum) from California, presented by Mr. C. IL Hastings ; 

 a Daudin's Tortoise {Testudo daudini) from the Aldabra 

 Islands ; a West African Python [Python seba) from West 

 Africa, deposited; a King Vulture [Gypagus papa) from South 

 America ; a Bronze-winged Pigeon [Phaps chalcoptera) from 

 Australia, purchased; a Peacock VhQZ.S2xit [Polyplectronchinquis), 

 bred in the Gardens. 



OUR AS TRONOMICA L COL UMN. 



New Observations of Venus.— During the first three 

 months of the present year, Dr. Eduardo Fontsere, of the Observ- 

 atory of the Royal Academy of Sciences, Barcelona, made a 

 series of observations of the planet Venus with a refractor of 

 II cm. belonging to that observatory. An account of these 

 observations is briefly described in the current number of the 

 Astronomischen Nachrichten (No. 3430), and is accompanied by 

 numerous figures illustrating the different surface markings that 

 were recorded. The colour of the planet was noted as being of 

 a yellowish green tinge, the most brilliant regions of the disc 

 being less coloured than the others. The polar regions were not 

 found to resemble those on Mars. Attention was paid especially 

 to the dark and light spots on the disc, which were at times very 

 conspicuous. We cannot here enumerate the various differences 

 of shade observed, but we may mention the most brilliant 

 noticed, namely, that situated near the south pole, and forming 

 the letter X by the crossing of two arcs of circles. Dr. Fontsere 

 classifies the bright regions into two divisions : those which 

 are, to 'all intents and purposes, permanent, but of a variable 

 nature, increasing and decreasing in relative brightness between 

 certain limits ; and those which appear like white trails always 

 inclined towards the equator, but never parallel to it. As in the 

 observations of Trouvelot, large deformations of the terminator 



NO. 1448, VOL. 56] 



were distinctly noticed, but are attributed for the most i)art to 

 irradiation. The extremities of the horns were also found to be 

 sometimes prolonged into the non-illuminated portion of the 

 disc. The observations during these three months have indi- 

 cated that, relatively to the sun, Venus has not undergone any 

 rotation except as regards the small libration, which was exactly 

 equal to that which corresponded to the change of geocentric 

 latitude. The above-mentioned observations form a valuable 

 contribution to our present knowledge concerning the telescopic 

 appearance and time of rotation of this planet. 



The Yerkes Observatory. — In the June number of the 

 Astrophysical Journal, Prof. Hale brings to a conclusion his 

 series of articles on the Yerkes Observatory and Telescope. 

 The concluding article is elaborately illustrated, showing the 

 telescope and dome in various stages of construction, the 

 frontispiece illustrating the stage reached on May 1 1 last. We 

 notice that the dedication of the observatory will take place on 

 October i next, and it is hoped " that European men of science 

 who propose to attend the Toronto meeting of the British 

 Association in August, may think it desirable to take part in 

 the formal inauguration of the Yerkes Observatory. ... It is 

 planned to hold a series of informal conferences on astronomical 

 and astrophysical subjects, ... A cordial invitation is hereby 

 extended to all men of science who may be willing to honour 

 the observatory by their presence on this occasion." 



Resolving Power of Spectroscopes. — In this column, on 

 May 20 (p. 62), we referred briefly to Prof. Wadsworth's investiga- 

 tions on the question of the theoretical resolving power of optical 

 instruments, in which he distinguished between four different 

 cases. In this work he obtained formulae which gave the three 

 different resolving powers, namely, (i) / (theoretical) for a wide 

 slit and monochromatic radiations,'; (2) R (limiting) foran infinitely 

 narrow slit, but for lines of finite width A\; and (3) P (practical) 

 for a wide slit and non-monochromatic radiations ranging for each 

 line over a small value AA. In the current number of the 

 Astrophysical Jotirnal (vol. vi. No. i), he now publishes tables 

 which he has prepared, giving the values of /, R and P for 

 values of r, which gives the value of the theoretical resolution 

 of the instrument for an infinitely narrow slit and infinitely 

 narrow spectral lines. In these tables r ranges from 25,000 to 

 1,000,000, AA. from O'Oi to I "oo tenth metres, s (linear width 

 of slit) from 0005 mm. to 0*3 mm, and ^ (angular magnitude 

 of collimator as viewed from slit) from 1/40 to i/io. All the 

 values are computed for A = 5500 tenth metres, this being 

 the mean wave-length of the brightest part of the visible spectrum. 

 Prof. Wadsworth adds also a complete explanation of the use 

 of these tables, and numerous important remarks. 



The Horizontal Gyroscope. — Attempts have several times 

 been made to eliminate the use of the horizon when employing 

 a sextant on board ships, by adopting mechanical or other 

 means of determining the horizontal or vertical. Among these 

 may be mentioned the pendulum in a collimator devised by 

 Colonel Goulier, the mercury siphon of M. Renouf, and other 

 ingenious devices suggested by Lejeune, Cardan, &c. None of 

 these seems, however, to have come into practical use, and the 

 mariner is still using the sextant in its ordinary form. Another 

 rather novel mode of determining the horizontal is described by 

 M. Gz.S'psixi'mx.ht /ournal de Physique (\o\. vi. p. 229). This 

 idea was proposed by Rear-Admiral Fleuriais, and from all 

 accounts seems to be of practical use. It consists in making a 

 small addition to an ordinary sextant by mounting in front of 

 the telescope and behind the small mirror a horizontal gyroscope 

 which contains on its upper part two small plano-convex lenses, 

 equal in all respects, placed a distance apart equal to their 

 focal length. On the plane faces of these lenses are engraved 

 two lines parallel to the equator of the gyroscope, and this 

 plane contains their optical centres. The gyroscope is given a 

 motion of rotation from 80 to 100 turns a second under some 

 conditions. The horizontal is obtained by observing the posi- 

 tion of the locus of these lines as the lenses revolve. To 

 describe the method of working, and give an idea of the theory 

 of the instrument, would occupy too much space in this column. 

 We may mention, however, that the instrument has been used 

 both on land and sea, and the officer who made the experiments 

 " est arrive a etablir que I'appareil est definitivement devenu 

 pratique." With a telescope magnifiying from 3 to 4 diameters 

 an approximation of 2' was obtained under ordinary conditions 

 of observation, but generally greater accuracy than this was 

 secured. 



