50 



NATURE 



[December 19, 1895 



LETTERS TO THE EDITOR. 

 [ The Editor does not hold himself responsible for opinions ex- 

 pressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part of Nature. 

 No notice is taken of anonymous communications. 1 



Intensity and Quantity of Sunheat at Different 

 Zones. 



The following figures may interest readers of Nature. They 

 give the relative summer and winter intensities of sunheat for 

 every five degrees of latitude, i.e. the sunheat per square foot — 

 and also the relative total quantities of heat received at the zones 

 extending from o°-5°, 5°-iS°, &c. 



Latitude _ o" 5° 10° 15° 20° 25° 30° 35° 40" 45° 



Summer Intensity 943 971 997 1016 1026 1030 1026 1016 997 973 

 Winter Intensity 961 915 866 808 752 694 634 569 498 423 



Latitude 50° 55° 60° 65° 70° 75° 80° 85° 90° 



Summer Intensity 947 909 868 840 821 806 793 780 766 

 Winter Intensity 345 269 197 135 79 40 18 5 o 



Zone o-s° 5-15° 15-25° 25-35° 3S-45'> 45-55° 55-65" 6s-75° 75-85° 



Summer Heat 478 987 964 886 764 612 434 286 84 



Winter Heat 469 857 707 550 331 269 100 27 q 



The figures are not guaranteed as accurate to the last place, 

 but that place is included so that the totals may be fairly correct 

 when we take the total sunheat over several zones. Thus we 

 get the summer and winter sunheat up to latitude 30° in the 

 ratio of 30 to 23, while from the cap from 30° to the pole the 

 quantities are 25 to 10, on the same scale. Again the summer 

 and winter proportions from o°-45° and 45°-90° are 43 to 29 

 and 12 to 4 respectively. 



The proportion of the summer and winter sunheats received 

 by the entire hemisphere is obtained as 55 to 33, the unit being 

 the same as before. That these two are almost exactly in the 

 ratio of Ball's and Weiner's numbers, 63 to 37, may be regarded 

 as a sufficient check on the accuracy of the figures, which were 

 calculated separately. E. P. Culverwell. 



Trinity College, Dublin, November 25. 



The Discovery of the Anti-Toxin of Snake- 

 Poison. 



In reference to the statements contained in Prof Ray 

 Lankester's letter in your issue of December 12, I have 

 to point out that no claim of priority has ever been advanced 

 by me. 



Hitherto my communications have been of the nature of 

 preliminary statements, and in such communications it is neither 

 possible to enter into details of the work done by others on the 

 same subject, nor usual to attempt to do so. 



On each occasion in which I have described the results of my 

 experiments, I have briefly referred to all previous workers on 

 the subject, in so far as they were known to me ; and, in par- 

 ticular, I have definitely mentioned, or otherwise drawn attention 

 to the circumstance that, before I had been able to do so, M. 

 Calmette had published evidence showing that animals could be 

 immunised against snake-venom, and that the blood-serum of 

 those animals possesses antidotal properties. 



At the same time, the work done by me was absolutely in- 

 dependent in its conception. It was originated several years ago, 

 and has been carried out on a plan and with aims which were 

 formed independently of the work of any other experimenter. 

 That part of it which has as yet been described in the published 

 abstracts had for the most part been completed before M. 

 Calmette's paper announcing successful immunisation had come 

 to my knowledge. I have rarely had occasion to consult Pasteur's 

 Annates, and thus it happened that M. Calmette's paper was 

 noticed only when the literature of a different and purely bac- 

 teriological subject was being collected for me. As to the articles 

 in the Cetitemporary Review, I have not seen them, nor did I 

 know of their existence until they were mentioned by Prof. 

 Lankester. Thomas R. Eraser. 



Edinburgh, December 16. 



NO. 1364, VOL. 53] 



" Pithecanthropus erectus " and the Evolution of the 

 Human Race. 



The remarkable advance made by biology during the las: 

 twenty years in the study of the Tertiary mammalia, must 

 strike even the most casual onlooker. It is not merely that ar» 

 exact knowledge has been gained of a vast number of extinct 

 forms, but that amongst these has been discovered a profusiort 

 of missing links, rendering possible the construction of ancestral 

 trees, or diagrammatic illustrations of the successive stages 

 through which existing animals may have been evolved from a 

 common stock. Some of these " trees" may prove to be mere 

 intellectual weeds, which to-day are, and to-morrow are cast 

 into the oven ; but others are of robuster growth, finding a firm 

 support in geology, which has been able in many cases to cer- 

 tainly fix the order in which successive branches of the tree have 

 budded forth. It is to be regretted that geology has not been 

 able to do more than this ; could it but succeed in the, con- 

 struction of a scale of past time, what fascinating prospects in 

 the study of evolution would be opened out ! The construction 

 of such a scale is beset, however, by grave — possibly insur- 

 mountable — difficulties, as will readily appear from the following 

 attempt. 



For the present there appears little hope of connecting geo- 

 logical events with such astronomical processes as changes of 

 eccentricity and the precession of the equinoxes, and the only 

 method left for our adoption is that of estimating the maximum 

 thickness of the successive systems of stratified rocks. This, 

 however, is to a great extent vitiated at the outset by the 

 heterogeneous character of these systems ; some are wholly or 

 in part marine, some fluviatile ; some consist largely of organic, 

 others of mechanical sediment ; and it is impossible to reduce 

 their various members to any common term. 



As there is no alternative, we proceed to do the best we can 

 with existing materials, and shall now endeavour to obtain some 

 approximate notion of the relative duration of the last three 

 periods in the earth's history, viz. the Pleistocene, Pliocene, and 

 Miocene. The first and most recent of these was probably of 

 longer duration than we are accustomed to suppose. Borings sunk 

 in the deltas of existing rivers have seldom penetrated to the 

 bottom, yet they have indicated a very considerable thickness- 

 of deposits ; thus, in the case of the Po, a boring near the Casa 

 di Dio, Venice, passed through 572 feet of sediment. Near 

 New Orleans, the delta of the Mississippi was penetrated for 

 630 feet ; while the fluviatile deposits of the Ganges were shown, 

 by a boring near Lucknow, to exceed 1336 feet in thickness. 

 In Alaska, however, as the observations of Russell prove, the 

 Pleistocene attains a far greater thickness than this ("Second 

 Expedition to Mount St. Elias in 1891." U.S. Geol. Survey, 

 Thirteenth Report, part ii. p. 24, 1891-2). 



The following extracts from his report may prove generally 

 interesting : — "The Chaix hills are geologically unique. They 

 are formed of a monoclinal block of conformable strata eight or 

 ten miles long, trending north-east and south-west, and tilted 

 northward at an angle of 10° or 15°. . . . But what makes- 

 the hills especially interesting to the geologist is the fact that 

 they are composed of stratified morainal material. . . . From 

 many eye estimates it is evident that the minimum thickness of 

 the deposit cannot be less than 4000 or 5000 feet. The rocks 

 are essentially homogeneous from base to summit, and are com- 

 posed of sandy clay containing large quantities of both angular 

 and rounded boulders of all sizes up to six or eight feet ir> 

 diameter. In the finer portions of the deposit . . . sea-shells 

 are numerous. A small collection was made. . . . All [the 

 species] are still living in the adjacent ocean. Besides the shells- 

 of molluscs, there are the shell-cases of annelids {Serpula?'\ 

 attached to glaciated boulders, showing that the stones on 

 which they grew must have remained exposed at the botton> 

 of the sea for some time before being wholly buried.'' 



It may be objected that these deposits differ so completely 

 from those of the alluvial plain of the Changes, in their nature 

 and origin, that they might fairly be left out of account ; but 

 to this it may be replied that we have no reason for supposing 

 that glacial denudation proceeds at a greater rate than fluviatile, 

 indeed the reverse is probably nearer the truth, and though it is- 

 deposition and not denudation which is directly in question, yet 

 the observation of Mr. Russell, that annelid tubes are found 

 adhering to the embedded boulders of the deposit, certainly does 

 not suggest an excessively rapid rate of accumulation. We 

 shall take then 4000 feet as representing the maximum thick- 

 ness of the Pleistocene system. 



