no 



KNOWLEDGE. 



[May 1, 1900. 



visible to the naked eye, and yet felt that he had not 

 even then reached the highest. 



The morning had been clear and bright, but at the 

 time of this occurrence the east sky was covered with 

 a thick thundery-looking haze. There was no surface 

 wind. Barometer steady at about 30.2 inches. 



Wallingford,, Berks. T. H. Astburv. 



LONDON SUMMERS. 



TO THE EDITORS OF KNOWLEDGE. 



Sirs, — A short time ago I offered some evidence for 

 a connexion between our summers and the sunspot cycle 

 of about eleven years. While still of oijinion that 

 much may be said for this view, it has of late seemed 

 to me worth consideration whether a shorter period, 

 Bay of about ten years, might not give a better account 

 of the facts. 



Perhaps you will allow me to supplement that article 

 with a diagram in which the fifty-nine Greenwich 

 summ?rs, 1841-^9, are grouj)ed according to the number 

 in which the year ends (years ending in 0, in 1, in 2, &c.. 

 and so on nj) to 9). Each dot represents a summer 



i6~ 



Distribution of 59 Suminevs (CTivenwirli) in 10 ('ohimns. 



season, aj^d shows by its jjosition how many davs with 

 temperature 80° or more it had. The average is 15 

 (represented by a line). 



(As the series begins with 1841, the column is one 

 dot short.) 



One is struck, I think, by the greater coolness, gene- 

 rally, in the earlier part, and the general rise in 

 position of the dots as the decade advances to the 6-8 

 groups. 



The averages of the columns come out as follows: — 

 0. 1. 2. :;. t. .i. i;. 7. s. 9. 



10-2 10-5 12-5 12-3 152 12'5 19-8 208 157 16-0 

 Thus the summers of yeai's ending in 7 have had, 

 on an average, more than twice as many of those hot 

 days as the summers of years ending in 0. 



Four of the first five values are below the general 

 average; four of the last five values above it. 



From this point of view, then (and it is a purely 

 empirical one), cool summers seem to be more probable 

 than hot ones in the immediate future, and we should 

 hardly expect any extremely hot ones. It remains to 

 be seen whether the next sixty summers will have tho 

 same general distribution as those now considered 



Other facts pointing in the same direction might, I 

 think, be given, but I will not here enlarge on the 



subject. Alex. B. MacDowall. 



♦ 



OuNdnui.OGiCAL XoTES. — In the absence from England of Mr. 

 Harry F. Withcrhy, the Ornithologifal Notes are held over. 



— ♦ — 



Science loses one of her chief ornaments by the death 

 of Professor St. George Mivart, f.r.s., who exjjired on 

 the 1st April, 1900. Born in November, 1827, he was 

 educated at Clapham Grammar School, Harrow, and 

 King's College, London. In 1851 he was called to the 

 Bar, but, attracted by scientific studies, he became lec- 

 turer at St. Mary's Hospital Medical School in 1862. 

 Dr. Mivart was at variance with Darwin as regards 

 " natural selection " and evolution as applied to the 

 human intellect, and in the early seventies engaged much 

 in controversy on these subjects, always with great liter- 

 ary skill, however his opinions might differ from those of 

 his opponents. In 1867 he was elected a Fellow of the 

 Royal Society, and in 1869 he became Vice-Pi-esident 

 of the Zoological Society. Dr. Mivart was an accom- 

 plished lecturer, well known in that capacity, not only 

 in London but throughout the country. Among his 

 works may be mentioned " The Genesis of Species," 

 1871; "Lessons in Elementary Anatomy," 1872; 

 "Man and Apes,'' 1873; "Lessons from Nature" and 

 " Contemporarv Evolution," 1876; "The Cat," 1881; 

 " Nature and thought," 1883 ; " The Origin of Human 

 Reason," 1889. Dr. Mivart's last days were occupied 

 by a controversy with the heads of his church. The 

 coi-respondence in the " Times " of January 27 and 29, 

 1900, indicated that for some years a conflict had been 

 steadily growing in his mind between the force of private 

 judgment and the necessity of submission to authority. 



Professor John Henry Pepper, who died last month 

 in his 80tli year, attained fame by means of the " ghost 

 illusion " which in the sixties was very much in vogue 

 at the theatres. At the Polytechnic in Regent Street 

 the exhibition succeeded both scientifically and as a com- 

 mercial enterprise. Prof. Pepper was the author of se\7eral 

 popular science books, and these, together with his skill 

 as a lecturer, did much to attract public attention to 

 science subjects. " Pepper's Ghost " is said to have 

 been suggested to the inventor by observing the images 

 of his fellow passengers while riding home in a train 

 late at night, the glass windows reflecting their faces 

 on the " darkness " outside. 



ilottccs^of_Boofts. 



" Photographs of Stai-s, Star -Clusters, and Xebula?, together with 

 Records of Results obtained in the Pursuit of Celestial Photo- 

 graphv." Bv Isaac Roberts, d.sc, p.r.s. Volume II. (London : 

 Knowledge" Office. 326. High Holborn. W.C.) 1899. Price 30s. 

 It is a very difficult matter for astronomers living at the present day 

 to fully estimate the value of Ur. Isaac Koberts' series of stellar 

 and ntljular jliotographs of which the second voUune has just b^en 

 issued. Th;it tliey are very beautiful photographs of beautiful and 

 wonderful objects is clear ; it is patent to the mo.st casual glance. 

 That they will amply repay the study of Dr. Dreyer (in whose hands 

 we believe that copies have been placed for examination) will soon 

 also be evident. But it is only a few of their secrets that will be 

 disclosed by the study of some months or years, and it will be for 

 future generations to fully understand the value of the work wliich 

 Dr. Roberts has undertaken. Dr. Roberts has himself foreseen this, 

 and has felt it necessary that the photographs should be printed 

 in permanent ink, for not only are the original glass negatives liable 

 to be lost by accidental breakage, but he finds that, " after the 

 lapse of a limited number of years the gelatine films will become 

 discoloured, the images will fade, and the faint stars and the faint 



