314 



NATURE 



[June 19, 1919 



The observations with the Cookson floating zenith- 

 telescope have been carried on throughout the war, 

 and the result of a discussion of seven years' observa- 

 tions with the instrument was presented to the Royal 

 Astronomical Society on June 13. Besides a deter- 

 mination of the variation of latitude at Greenwich, 

 which may be considered trustworthy, as the discord- 

 ances from a smooth curve rarely exceed a few 

 hundredths of a second of arc, the observations also 

 furnish a value of the aberration constant, which, de- 

 duced from the seven years' observations, is 20-442", 

 corresponding to a solar parallax of 8-815". The 

 values derived from the observations of individual 

 years show rather a large range, and the possibility 

 of systematic disturbing causes is being investigated. 



Turning to the equatorials, the 28-in. refractor was 

 at the disposal of M. Jonckheere until he returned to 

 his home in Lille in Januaiy last. The observations 

 of double-stars made by M. Jonckheere have been pub- 

 lished in the Astronomical Journal. The object-glass 

 of the 26-in. refractor, which had been dismounted in 

 September, 1917, was replaced on October 15, 1918, 

 and photographs of the Galilean satellites of Jupiter 

 were taken on twenty-six nights during the apparition 

 of last winter for Dr. de Sitter, who is making a 

 research on the elements of their orbits. Photographs 

 for stellar parallax have also been taken with this 

 instrument. The 13-in. object-glass of the astro- 

 graphic telescope is now in Brazil, having been used 

 in observation of the eclipse of May 29. With this 

 instrument a series of photographs were taken of the 

 nova which appeared in Aquila in June, 19 18, to 

 determine its variation of magnitude in the subsequent 

 months. The work of the Astrographic Catalogue is 

 being supplemented by determination of the proper 

 motions of the stars contained in it by comparison 

 with earlier catalogues, and also by direct comparison 

 of pairs of plates taken at an interval of about twenty 

 years. 



The record of the sun-spots has been continued, and 

 photographs of the sun were obtained on 208 days. 

 The measurement and reduction of the sun photo- 

 graphs for 19 17, the series being completed by photo- 

 graphs taken at the Cape, is in progress. During the 

 period covered by the report the activity of the sun 

 has been considerable, but there has been, on the 

 whole, a perceptible decline since the great disturb- 

 ances of August, 1917. 



The mean values of the magnetic elements for 1918 

 and three previous vears are as follows : — 



Dec. W. Horizontal Vertical Dip 



Q , force force o / 



1915 ... 14 56-5 0-18508 0-43315 66 51-8 



19 16 ... 14 46-9 0-18494 0-43313 66 52-7 



19 17 ... 14 37-0 0-18477 0-43305 66 53-6 



19 18 ... 14 27-2 0-18462 0-43290 66 54-2 

 The annual diminution of declination increased 



considerably about 19 10, its average value from 

 1900-10 being 4-9'. Ihe horizontal force which had 

 been increasing since measurements were begun at 

 Greenwich in 1846 reached a maximum about 19 10, 

 and is now diminishing. The dip which had been 

 diminishing since measurements were begun in 1843 

 reached a minimum about 1913, and is now increasing. 



The principal meteorological features reported for 

 the year ended April 30, 19 19, are : — The mean tem- 

 perature was 49-5°, or 0-1° below the average of the 

 seventy-five years 1841-1915. The highest tempera- 

 ture in the shade was 89-8° on August 22, and the 

 temperature exceeded 80° on six days. The lowest 

 temperature was 15-5° on February 9, and on fifty- 

 five days it fell as low as 32°. 



The duration of bright sunshine registered _ was 

 1436 hours out of a possible 4456 hours. The rainfall 

 was 31-14 in., or 6-90 in. above the average for the 

 NO. 2590, VOL. 103] 



period 1841-1915. The number of rainy days (0-005 in. 

 or more) was 194, the largest number for thirty-six 

 years; 7-34 in. of rain fell in July, 1918. 



The work of rating and issuing the chronometers 

 for use of the Navy has been excessive. During the 

 year 8631 chronometers and watches were received 

 and 6713, issued. The number sent for reoair was 

 2990. The corresponding figures in the reporl of 19 14 

 were 2094, 2 no, and 934 respectively. The wooden 

 time-ball on the observatory is to be replaced by one 

 of aluminium, and the work is now in progress." 



The report ends with a reference to the system of 

 time-zones for time-keeping at sea, which the Lords 

 of the Admiralty have decided to establish in H.M. 

 Navy; also to the substitution of a day beginning at 

 oh. midnight for the astronomical day in all nautical 

 publications. The Admiralty has decided that the 

 alteration shall be made in the "Nautical Almanac" 

 beginning in the year 1925, and in the "Admiraltv 

 "Tide-Tables" for 1920. 



THE SOUTH-EASTERN UNION OF 

 SCIENTIFIC SOCIETIES. 

 'T'HE twenty-fourth annual congress of the South- 

 /- Eastern Union of Scientific Societies was held 

 in the Guildhall, London, on June 11-14, under the 

 presidency of Dr. A. Smith Woodward. In his 

 opening address the president referred especially to ■ 1 

 the pioneer work of Mantell in discovering the fossil f I 

 giant reptiles in the Sussex Weald, and showed how * | 

 the later finds in Belgium and North America had 

 partly modified, partly extended, his conclusions. He 

 mentioned that Mr. Reginald W. Hooley had recently 

 found in the southern cliffs of the Isle of Wight a 

 skeleton of an iguanodon which rivalled those from 

 Bernissart, Belgium, in perfection. The specimen 

 showed a finely granulated skin. The sudden ending 

 of the "geological age of reptiles," as Mantell named 

 It, still awaited explanation, for the distribution of 

 the giant reptiles was almost world-wide at the time. 

 The mammals found the land practically vacant for 

 occupation, and none of them attained a larger size 

 than a tapir until the Middle Eocene period. 



Mr. L. W. Chubb described the woodlands of 

 London, and showed the importance of the work of 

 the Commons and Footpaths Preservation Society. 

 The congress passed a resolution urging the London 

 County Council to secure Castle Wood on Shooter's 

 Hill, Woolwich, as a public resort. Dr. A. B. Rendle, 

 in an address to the botanical section, referred to the 

 facilities for research at the South London Botanical 

 Institute, which was founded by the late Mr. A. O. 

 Hume. It was important to "compare the British 

 flora in detail with that of the European continent, 

 and much remained to be done in studving growth- 

 stages. _ Mr. C. C. Fagg reported on progress with 

 the regional survey, and showed several maps on 

 which he had plotted records in the neighbourhood of 

 Croydon. Mr. Reginald A. Smith exhibited a map 

 of London on which he had marked the finds of 

 Palaeolithic implements in their relation to the river- 

 terraces. The Rev. T. W. Oswald-Hicks showed a 

 series of lantern-slides illustrating the life of mos- 

 quitoes, which he had prepared, to be lent to the 

 societies of the union. In this way he hoped to spread 

 an interest in the subject and enlist the help of more 

 observers and collectors of mosquitoes. Mrs. Plomer 

 Young mentioned that several thousand lantern-slides 

 illustrating natural history were now at the disposal 

 of the union, and could be borrowed by the constituent 

 societies. Sir Edward W. Brabrook was elected 

 president of next rear's congress, which is to be held 

 at Eastbourne. 



