Oct. 26, 1888.] 



SCIENTIFIC NEWS. 



439 



—or at least one small group of facets conveying a 

 common impression — is employed at any given moment, 

 and that the remainder see only in a blurred and con- 

 fused manner, just as we ourselves dimly see neigh- 

 bouring objects when gazing into the far distance. This 

 is more probable ; but in the present incomplete condi- 

 tion of our knowledge it is quite impossible to pronounce 

 upon the point with any degree of certainty. 



Eyes of a third description we find in certain aphides, 

 in the form of supplementary " eye-tubercles," two in 

 number, one of which is situated at the corner of each 

 of the compound eyes. These eye-tubercles are fur- 

 nished with from five to ten facets apiece, differing little, 

 structurally speaking, from those of the compound eyes, 

 but hemispherical instead of hexagonal. Their particular 

 function is altogether unknown, as is also the reason why 

 aphides, which are for the most part very sluggish 

 creatures, should possess numerous and well-developed 

 eyes, and in three forms instead of in two. But then 

 aphides are in many ways most exceptional beings. 



Seeing, then, the highly-developed character of the 

 eyes of insects, their invariable presence in those species 

 to which they could by any possibility be of service, 

 and the utter absence of proof to the effect that their 

 range of vision is so limited as has sometimes been con- 

 tended, we may surely concede that sight is the most 

 important of an insect's senses, and that it is generally 

 present in a very remarkable degree. 



On the Distribution of Rain over the British Isles during 



the YeanSSj, as observed at more than 2,500 Stations 



in Great Britain and Ireland, tvith Articles upon various 



Branches of Rainfall Work. Compiled by G. J. 



Symons, F.R.S. London : Edward Stanford. 



The author remarks in his preface that the year 1887 



seems to have had no equal for wide-spread deficiency of 



rainfall since 1788 ! He further expresses the opinion 



that " if the drought from 1738 to 1762, indicated by the 



observations already collected, is real and recurs, not only 



will every town in England which receives its water 



supply from a gathering-ground be put on short supply, 



but the canals will have to be closed and agricultural 



operations v. ill have to be modified." 



This passage was, of course, written before the present 

 season declared its character. There is now little fear of 

 a short water supply or of the closing of canals, and 

 as to agricultural operations they seem in danger of 

 being suspended altogether. In his first chapter the 

 author endeavours to give a fixed meaning to the terms 

 "absolute droughts" and "partial droughts." By the 

 former he proposes to understand times of more than 

 fourteen days absolutely without rain. The partial 

 drought is to signify times of more than twenty-eight con- 

 secutive days, the aggregate rainfall of which does not ex- 

 ceed o - oi in. daily. A further form of drought receives the 

 rather curious name of " engineers' drought," that is, a 

 drought which an hydraulic engineer must provide 

 against in drawing up a scheme for a water suppty, 

 and such drought he defines as a time of " three or more 

 consecutive months, the aggregate rainfall of which does 

 not exceed half the average." 



The account of " historic droughts " in the British 

 Islands, from the third century downwards, is especially 

 in its earlier parts, open to doubt. In our days "burn. 



ing summers," "scorching heat," etc., are exceedingly 

 rare phenomena. 



The observations made last year show a striking 

 deficiency of rainfall, the aggregates ranging up to 17 in. 

 below the averages of former periods. The heaviest fall 

 recorded in any twenty-four hours is that at Queen's 

 College, Galway, on September 1st, amounting to 4^93 in. 

 The accounts of the water famine prevailing during 

 September in various parts, both of England and Ireland, 

 are very striking. In most parts of the British Isles, 

 however, the dry weather was not accompanied by any 

 unusual heat. Chilly polar winds counteracted the effects 

 of bright sunshine by day, and, as we learn from other 

 sources, the temperature, save perhaps in July, was from 

 2 to 3 Fahr. below the average. 



The Scientific Proceedings of the Royal Dublin Society. 

 Vol. V. (N.S.), Parts 7 and 8. July and November, 

 1887. Vol. VI. (N.S.), Parts 1 and 2. February 

 and May, 1888. 



The subjects considered in the parts before us are 

 chiefly either of a geological or a physical character. 

 Mr. A. B. Wynne treats of submerged peat-mosses and 

 trees in certain lakes of Connaught. The author, to 

 account for tree-stumps standing erect under water as 

 if they had grown there, suggests that the stools of 

 the trees in the bogs with horizontal roots retained their 

 position until the boggy ground they grew in had been 

 almost entirely removed. In case of an unusual storm 

 the remaining roots snapped or drew, and each water- 

 logged mass subsided to the bottom, settling upon its 

 broadest surface still in its natural position of growth. 



Mr. G. H. Kinahan, M.R.I. A., discusses the deal 

 timber in the lake basins and peat-bogs of north-east 

 Donegal, with especial reference lo the fact that the 

 stumps, locally called " corkers," are found in situ below 

 the present level of natural drainage. He formerly 

 thought that the flooding of the hollows might be due to 

 beavers. He notes, however, that in Irish, unlike 

 Welsh or Gaelic, there is no name for a beaver, and he 

 has not been able, in Donegal, to recognise any beaver 

 workings, with the features of which he has become 

 acquainted in Canada. He now, with Mr. Plunkett, 

 holds that the trees grew in flats and hollows without 

 drainage outlets in periods when the climate was 

 hotter and drier than at present. When a wetter and 

 colder epoch succeeded the flats and hollows became sub- 

 merged. 



Professor Hall, F.R.S. , communicates an important 

 paper on the " Effect of Continental Land in Altering 

 the Level of the Ocean." The author quotes the opinion 

 of Professor Ed. Suess, expressed in " Das Antlitz 

 der Erde," that the surface of the ocean along the 

 margin of a continent may be as much as 3,300 feet 

 higher than the surface along the shores of a mid- 

 oceanic island. The difference of level along the coast 

 of Mexico and at the Sandwich Islands is said to be no 

 less than 4,520 feet. 



Professor W. J. Sollas, in a contiibution to the " His- 

 tory of Flints," concludes that a bed of average-sized 

 flints may be formed in about fifty years, more or less — 

 a much shorter time than would have been expected. 



R. F. Scharff, Curator of the Natural History Depart- 

 ment in the Dublin Museum, reviews Dohrn's theories 

 on the origin of the vertebrates. Dohrn draws attention 

 to the fact that his views differ from the current ideas in 

 three main points : the derivation of the vertebrates from 



