ii4 



HARD WICKE ' S S CIENCE- G SSIP. 



("Geological Magazine," April). — "On the Micro- 

 scopic Fauna of Elevated Alpine Lakes," by Dr. O. 

 E. Imhof(" Annals and Mag. Nat. Hist." April).— 

 " De la Recolte et de la Conservation des Entomo- 

 straces d'eau douce," par J. Richards (" Feuille des 

 Jeunes Naturalistes," April). "The Significance of 

 Sex," by Julius Nelson ("American Naturalist," 

 Jan. and Feb.) " A New Departure in the Study 

 of Minerals," by Professor C. F. Marsan ("Trans. 

 Ottawa. Field Naturalists' Club," 1887.) " Prim- 

 roses," by W. B. Ffemsley ("Nature," April 14th). 



OUR SCIENTIFIC DIRECTORY. 



Liverpool Science Students' Association, — President, 

 William Narramore. Secretary, John Braek Warriner, 

 la North John Street, Liverpool. Treasurer, Robert 

 H. Day. 



ASTRONOMY AND METEOROLOGY. 



A 



By John Browning, F.R.A.S. 



T the meeting of the Royal Astronomical 

 Society, held on March nth, some remark- 

 able photographs of a portion of the constellation 

 Cassiopeia by the Brothers Henry, and a photo- 

 graph of the Orion nebula taken with an ex- 

 posure of two hours, were presented to the Society. 

 Mr. Crossby exhibited a new form of measuring rod, 

 and Capt. Abney read a paper " On the Atmospheric 

 Transmission of Visual and Photographically Active 

 Light." The papers were valuable, and the discus- 

 sions which ensued thereon interesting, but both 

 bristle with technicalities, and it would be impossible 

 to summarise them in the space at my disposal. 



Dr. Elkin, an American astronomer, who was 

 present, gave an account of some work he had been 

 engaged on for the last year and a half in determining 

 the parallaxes of the principal stars in the group of 

 the Pleiades, and mentioned that it would take him 

 another year to complete his observations. 



At the meeting of the Liverpool Astronomical 

 Society, a paper was read on the absolute dimensions 

 of the star-cluster 13 Messier, between 17 and £ 

 Herculis. The number of stars in this cluster was 

 computed by Sir \V. Herschel at 14,000. If the 

 cluster were considered as a sphere full of stars, 

 assuming the total mass to be equal to twice that 

 of the sun, it would give an average diameter of 

 45,218 miles for each component, and each star in 

 this wonderful cluster might be separated from the 

 next by 9000 million miles. 



The " Sidereal Messenger," an American journal of 

 astronomy, says : — "As regards the Lick Observatory, 

 it may be interesting to some of our readers to know 

 how the great object-glass was packed for trans- 



mission from the Clarks to Mt. Hamilton. The 

 lenses were packed separately in 15 to 20 thicknesses 

 of soft, clean, cotton cloth ; next came a thick 

 layer of cotton, and then a layer of paper. These 

 packages were then put into wooden boxes lined 

 with felt. No nails were used near the glasses, 

 and the boxes were made the shape of the 

 glasses. These boxes were next enclosed in two- 

 others of steel and packed tightly with curled hair. 

 Each steel box was enclosed in another steel box, 

 the insides of which were covered with spiral springs. 

 Both steel boxes were air-tight and waterproof, and 

 the outer chests packed with asbestos to render them 

 fire-proof. Each was then suspended by pivots in 

 strong wooden frames with contrivances for turning 

 each chest one quarter round every day during the 

 journey to California. This is to prevent any mole- 

 cular disarrangement in the glasses and to avoid the 

 danger of polarization, it being feared that the jarring 

 of the train would disturb the present arrangement 

 of the molecules, unless the position of the glass 

 should be changed, and all lines of disturbance thus 

 broken up." 



The same journal contains the following : — 



"Rotation Period of the Red Spot on Jupiter.- — 

 From eight observations in the spring of 18S6, Prof. 

 Young deduces a rotation period for this object of 

 9 hrs. 55 min. 407 sec ± o - 2 sec. Comparing this 

 value with those of Prof. Hough for the four pre- 

 ceding oppositions, it appears that the remarkable 

 retardation of the period still persists. Prof. Young 

 also determined the period of a small white spot 

 in a higher latitude than the red spot (50 S.) and 

 found it considerably shorter than that of the red 

 spot (9 hrs. 55 min. iri4 sec.) ; it therefore seems 

 that there are spots on both sides of the red spot 

 travelling more quickly than it does. Prof. Young 

 also adds some remarks on the junction of the 

 southern belt with the red spot described by Mr. 

 Denning in the ' Observatory' for May 1886, p. 188." 



On May 1st, Venus will be at the least distance 

 from the sun at three hours afternoon. 



On May 5th there will be an occultation of 7* 

 Virginis 2* magnitude. The disappearance takes 

 place at o hr. 25 min. morning, and the re-appear- 

 ance at 1 hr. 8 min. in the morning. 



During May Mercury will be a morning star, 

 entering Aries about the 6th, and Taurus about the 

 20th. 



Venus will be an evening star, entering Gemini 

 about the 13th. 



Mars will be too near the sun for observation. 



Jupiter will be almost stationary in Virgo. 



Saturn will be an evening star in Gemini. 



Meteorology. — At the Royal Observatory, Green- 

 wich, the mean reading of the barometer for the 

 week ending 19th March, was 29.88. The mean 

 temperature of the air was 31.4 deg., and 9.7 below 



