i6o 



HARDWICKE'S SCIENCE-GOSSIP. 



in 1500 years. Under these circumstances he thought 

 that we could not suppose such great changes as we 

 know to have occurred could have taken place in only 

 six or eight times that period. 



The President suggested that Professor Prestwich 

 was not, by any means, the first person to lay down 

 fixed terms of years for the duration and date of the 

 Glacial period ; he found very definite terms laid 

 down by other writers, and merely indicated reasons 

 why these should be greatly reduced. 



The author did not attempt to fix actual definite 

 terms of years, but only to show that we must not 

 unhesitatingly accept such large measures of time, 

 especially when based, as they were, upon an assumed 

 and unproved necessity. He objected to remain in 

 that state of ignorance with reference to time which 

 some of the speakers seemed to find quite satisfactory. 

 He referred to the observations of the Danish observers 

 on the Greenland ice, as furnishing us with certain 

 definite time-results, the application of which might 

 be expected to settle the question. It was a simple 

 rule-of-three sum. If the Alpine date were supposed 

 to accord with terms of 80,000 and 160,000 years, 

 what are the numbers which should accord with the 

 Greenland data ? It is impossible to contend that it 

 would make no difference, which would be the 

 conclusion implied by the observations of some of 

 the speakers. 



RECENT ARTICLES AND PAPERS WORTH 

 READING. 



" ' I "HE [Economic r Geology of Ireland. No. 1. 

 -L Metal Mining," by G. H. Kinahan (" Jour- 

 nal of Royal Geological Society of Ireland "). — 

 " American Jurassic Mammals," by Professor Marsh 

 ("Geological Magazine," June).— " Earthquakes," 

 by A. Ramsay ("The Garner," June).— " On 

 Tresca's Remarkable Investigations into the Flow of 

 Solids under Great Pressure," by W. P. Marshall 

 (" The Midland Naturalist," June).—" The Staining 

 of Animal and Vegetable Tissues," by A. J. 

 Doherty, and "Vision in Insects," by J. B. Petti- 

 grew (Trans. Manchester Microscop. Society). — 

 "History and Biology of Pear Blight," by J. C. 

 Arthur ("American Monthly Microscop. Journal," 

 May).—" President's Address" (R. Adkin) in 

 "Proceedings of South London Entomological 

 Society").— "Condensation of Gases,", by A. E. 

 Sutton ("Nature," June 2).—" A Contribution to 

 the Study of Well Waters," by Robert Warington 

 ("Journal of the Chemical Society," June). — "On 

 Leathery Turtles Recent and Fossil, and their 

 Occurrence in British Eocene Deposits," by A. 

 Smith Woodward ("Proc. Geologists' Association," 

 Feb.).—" Bridging the Firth of Forth," by B. Baker, 

 (Lecture delivered at the Royal Institution, reported 

 in "Nature," May 26). 



ASTRONOMY AND METEOROLOGY. 

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



AT the meeting of the Royal Astronomical 

 Society, on May 13th, Colonel Tupman de- 

 scribed some photographs of spectra of the stars 

 taken at the Harvard Observatory. The photographs 

 are greatly in advance of any which had previously 

 been taken, and they bid fair to enable the motion 

 of the stars which are approaching or receding from 

 us to be determined with much greater accuracy 

 then has hitherto been possible. Mr. Ranyard 

 explained that the spectra were taken without a 

 slit, by using four prisms which were placed in front 

 of the object-glass of a telescope; the spectrum of a 

 star as a mere line, without breadth, is thus thrown on 

 the photographic plate and this line has breadth given 

 to it by controlling the motion of the driving-clock. 



Mr. Knobel read a report of the English delegates 

 who were at the Congress of Astronomers held at 

 Paris on the 16th April to arrange for photographing 

 the stars. There were fifty-seven delegates in all, 

 eight of whom were English. It was unanimously 

 resolved to use only achromatic telescopes to take the 

 photographs, and that all the telescopes used shall be 

 of 35 centimetres, nearly 14 in. aperture. 



Mr. N. E. Green described the changes he had 

 observed in the markings on Jupiter and in the belts 

 of the planet during the last twenty-six years. From 

 i860 to 1868 the equator was occupied by a white 

 band edged with dark belts. From 1869 to 1S72 the 

 equatorial region was of a coppery hue, and the belts 

 were narrower. From 1873 to 1879 the coppery 

 colour was fainter, and from 1879 to the present time 

 a most perplexing series of changes in colour and 

 form have taken place. 



Between July 1st and the 2lst there is no darkness 

 as of night. On July 2nd the earth will be at the 

 greatest distance from the sun at nine hrs. morning. 

 July the 1 7th there will be an occultation of Aldebaran, 

 a star of the first magnitude. The disappearance 

 takes place at 3 hrs. 16 min. morning, and the re- 

 appearance at 3 hrs. 33 min. morning. 



Meteorology. — At the Royal Observatory, Green- 

 wich, the highest reading of the barometer for the 

 week ending 21st May was 30.20 in. at the beginning 

 of the week, and the lowest 29.08 in. on Friday 

 morning. The mean temperature of the air was 



48. 4 deg., and 5.6 below the average in the corre- 

 sponding weeks of the 20 years ending 1868. The 

 mean was below the average throughout the week, 

 the coldest day being Saturday, when the mean was 

 only 43.1 deg., and showed a deficiency of 11.9 deg. 

 The general direction of the wind was westerly. 

 Rain fell on four days of the week, to the aggregate 

 amount of 0.58 of an inch. The duration of registered 

 bright sunshine in the week was 33.3 hours, against 



45.5 hours at Glynd; Place, Lewes. 



