Oct. 9, 1879] 



NATURE 



571 



with a steam engine at some convenient place three or four 

 liundred yards away in an adjoining road, and the electro-motors 

 were also two Gramme machines, one on each side of the field, 

 with their coils revolving of course backwards. Through one 

 of these, the electric current was sent aIternately,'so that motion 

 was given to one or other of two large windlasses, one on each 

 of the waggons containing the electro-motors. In this way 

 the plough, which could be used going in either direction, was 

 first pulled across the field making a furrow, and then back 

 again making another parallel furrow." 



A photograph taken on the spot, of one of the complete 

 Gramme electro-motors, with its windlass and waggon, together 

 with the double acting plough, was projected on to the screen. 



A second photograph was also now projected on to the screen of 

 M. Chretien's electric crane for unloading boats. This too, the 

 lecturer said, had been successfully employed for several months 

 at Sermaize, in the harbour there, and it was considered that a 

 saving of about thirty per cent, had been effected of the expense 

 formerly incurred for unloading the sugar barrels out of the 

 boats. 



Reference was then made to the difficulty that would be 

 experienced in distributing electric power properly on account 

 of the current in any curcuit being affected by any alteration 

 in any other circuit connected with it, and it was explained how 

 this difficulty was met by the electric current regulations of 

 M. Hospiialier and Dr. Siemens. Another difficulty arising 

 from the velocity of the water on the hill streams being great 

 after floods and small in dry weather, and which at first sight 

 might appear to require an extravagant supply of dynamo 

 machines so that even in a draught sufficient power could be 

 transmittted electrically, it was explained, could be overcome by 

 storing up the electric energy as compressed gas, and it was 

 (ihown that a square foot of hydrogen at thirty atmospheres 

 pressure (the usual pressure in the iron gas bottles of commerce) 

 combining with half a cubic foot of oxygen, at the same pressure, 

 would develop no less than no million foot pounds of work. 



Prof. Ayrton concluded by asking : — 



" But is there no other side to this question ? We are, it is true, 

 a commercial people, but do we not still love our hills and our 

 fields? There was a time when the cutler of now black, grimy, 

 .Sheffield was very fleet of foot in following the chase. There 

 was a time when ' Not only in the villages around old 

 Sheffield,' so says the history of Hallamshire, ' were the file- 

 makers' shops or the smithy to be seen, with the apprentices at 

 work ; but even on the hill side in the open country, at the end 

 of the bam would be the cutlers' shed whilst in the valley below, 

 by the river, was the grinding wheel ready to sharpen the tools 

 that had been manufactured.' 



"And why not now? why should not that mountain air that 

 has given you workmen of Hallamshire in past times your sinew, 

 your independence of character, blow over your grindstone now ? 

 Why should not division of labour be carried to its end and power 

 brought to you instead of you to the power ? Let us hope then 

 that in the next century electricity may undo whatever harm 

 steam may have done during the last, and that the future workman 

 of Sheffield will, instead of breathing the necessarily impure air 

 of crowded factories, find himself again on the hill side, but 

 with electric energy laid on at his command." 



THE ANTIQUITY OF MAN 



A T the Sheffield meeting of the British Association Prof. 

 ■"• Boyd Dawkins, in the course of a paper "On the Antiquity 

 of Man, said he presented before them a diagram showing the 

 divisions of the tertiary period, the third of the three great lif« 

 l>eriods which had been presented on the earth. When he 

 examined those stages before the highest forms of life, he was 

 confronted with this most important fact : in the eocene age they 

 had not a single species of placental mammal, nor did they 

 meet with any indications of a living placental genus. No 

 species now found in Europe were found m the eocene age. It 

 was absolutely impos ible to suppose that man was living on the 

 tarth in eocene time, yet there was no reason, because of 

 climate and vegetation, that he should not have been. Then 

 they came to the miocenc age, when they found not merely living 

 families and orders, but living genera. Putting man out of the 

 question, there was not a single well-authenticated case on record 

 in any part of the world of any mammalian species" now living on 

 the earth having lived in the miocene age. The French pre- 

 served a flint flake which was found at Thenay, and which they 



say is of the miocene age ; in fact it was accepted by a great 

 majority of the French archaeologists that man was living in the 

 miocene age. The French held that flints found, and all of 

 them bearing traces of manufacture, were of the miocene age, 

 and the work of man. It was far less difficult to believe that 

 these flints were the work of some of the higher and extinct 

 forms of mokeys, than it was to believe that they were 

 the work of man. In the pliocene age they found one or 

 two living species making their appearance. Prof. Capelini had 

 called attention to the fact that certain cut bones, which v ere 

 asserted to be of the miocene age, had been cut by the hand of 

 man. On one of those bones there were cuts which were done 

 by the hand of man. The cuts were distinctly artificial, but the 

 difficulty which presented itself to his mind was this. He was 

 by no means certain that those bones, which were said to have 

 been fotmd in the pliocene strata, had been discovered in undis- 

 turbed pliocene strata. It was not clear to his mind that the 

 mineralisation of those bones would not take place long after the 

 pliocene age had passed away. He ui^ed his objections to the 

 accepting of specimens said to have been got in the pliocene age 

 when there was no good authority for saying that such was the 

 case. He then passed to the pleistocene, by some called the 

 glacial period. Then living species were very abundant, extinct 

 species very rare, and it was in that age that they met with man 

 in considerable abundance and scattered over a very wide area. 

 The evidence presented from time to time, in the first place out 

 of caverns, and on the other hand out of river deposits, showed 

 beyond a doubt that man was present in Europe in full force in 

 the pleistocene age, and he came in just when it might be 

 expected he would come in. In the pleistocene age they "met 

 with man as a mere hunter, not as a farmer or possessor of wild 

 animals. He mentioned that because during the last two or 

 three years it had been asserted that man was possessed of 

 domestic animals in the pleistocene period. The pre-historic 

 period which succeeded the pleistocene, was characterised by the 

 absence of the extinct species of mammalia, with one exception. 

 The one extinct animal which extended upward into the pre- 

 historic age was the Irish elk. The great characteristic of the 

 pre-historic age w as the calling in of the domestic animals, the 

 dog, sheep, horse, various breeds of hog, cattle — all coming in 

 under the care of man, all spreading over Europe ; and along 

 with them they had the getting of cereals and fruits, and the 

 cultivation of the arts of agriculture. They had in that period 

 just those very things which formed the foundation of that civili- 

 sation which they themselves spread, and which had been built 

 upon the foundations of the neolithic age. The pre-historic 

 period was divided into the neolithic, the bronze age, and the 

 age of iron. The prehistoric age was divided from the historic, 

 because the former was not represented to them in historic 

 records. In conclusion he ventured to express an opinion as to 

 how happy they would be if they could get hold of a date and 

 fix the antiquity of man in Europe in terms of years. It would 

 be most delightful if they could fix the first presence of man at 

 Creswell Crags, say within some thousands or hundreds of 

 thousands of years. He could not help thinkmg that all their 

 hopes of that description would ^be vain, as there were intervals, 

 and they could not know without the written record, the duration 

 of the intervals which separated one period from another. 



UNDERGROUND TEMPERA TURE ' 



THE temperature of the surface of the ground is not sensibly 

 influenced by the flow of heat upwards from below, but 

 is determined by astronomical and atmospheric conditions. The 

 rate of increase in travelling dovrawards from the surface may 

 conveniently be called the temperature gradient, and averages 

 about 1° F. for fifty or sixty feet. This is about five times as 

 steep as the temperature gradient in the air. 



If we draw isothermal surfaces for mean annual temperature 

 in the ground, their form beneath mountains and valleys will be 

 flatter than that of the surface above them. This is true even 

 of the uppermost; and the flattening increases as we pass to 

 lower ones, until at a considerable depth they become sensibly 

 horizontal planes. The temperature gradient is consequently 

 steeper beneath gorges and least deep beneath ridges. 



In a place where the surface of the ground and the isothermal 

 surfaces beneath it are horizontal the flow of heat will be vertical, 



' "On some Broad Features of Underground Temperature," by Prof. J. 

 D. Everett, F.K.S. Abstract of p«p« read at the Sheffield meetuig of th« 

 Biitish Association. 



