4o6 



NATURE 



{_Sept. 6, 1877 



On the Origin and Antitjuily of the Mounds of Arkansas, 

 U.S., by Prof. J. W. Clarke.— The mounds vary from three to 

 five feet high, and are from fifty to 140 feet in diameter. The 

 author suggests that they were evolved from the simple carn- 

 hillock by a race of men who followed the retreating glaciers. 



A Short Sketch of the finding of Silurian Rocks in Tcesdale, 

 by W. Gunn, F.G.S.— It has always been believed that no 

 rocks lower than the carboniferous limestone are exposed in 

 Teesdale. The recent work of the Geological Survey has 

 proved that certain peculiar beds at the Cronkley Pencil Mill 

 are not carboniferous, but silunan. Messrs. Gunn and Clough 

 have lately described these beds in a paper read before the 

 Geological Society. The notes submitted to the Association 

 record lurther discoveries of Silurian beds near Widdybank 

 Farm. They probably belong to the Stockdale series of pale 

 slates. 



Note on the Correlation of certain Post Glacial Deposits in 

 West Lancashire, by C. E. De Ranee, F.G.S.— This paper 

 described the post-glacial drifts of the Ribble Valley, and com- 

 pared them with the drifts of the Lancashire Plain. The sub- 

 merged forest of the coast and the peat of the plains are continuous 

 with the peat of the valley. They contain beech-nuts. The 

 Ribble has excavated its valley in glacial drift to a depth of from 

 150 to 200 feet ; the sea at the same time has cut back the coast, 

 forming a lowland plain on which the forest grew ; subsequently 

 the dr.iinage became obstructed and the peat was formed. A 

 subsidence of the land of some seventy feet or more submerged 

 the peat and forest. 



On the Influence of the Positions of Land and Sea upon a 

 Shijlino of the Axis of the Earth, by A. W. Waters, F.G.S.— 

 The author pointed out how the unequal distribuiion of land 

 and sea may be an agent in preventing the movements of eleva- 

 tion and depression of the land in one part of the globe, balancing 

 those in another, and further showed how similar movements in 

 various localities would differenily affect the pole. 



Any movement such as a submarine elevation which displaced 

 water would spread it over the oceanic area, and the effect of this 

 would, with the present configuration, be the same as if about 

 one-t-Aclfth of the weight had been added in the southern hemi- 

 sphere along 45° 44' long. E., viz., in a line passing by the 

 entrance of the White Sea over the Caucasus through the middle 

 of Madagascar. 



As every submarine movement would create a force acting in 

 this direciion there seems reasonable ground for thinking the 

 tendency would be for the shifting of the axis to take place near 

 this line. Dr. Jules Caret considers that the pole must have 

 moved approximately in a line passing through the meridian of 

 52° long. E., and what is cause, what effect, and how far they 

 react on one another, is fully worthy of examination by any 

 physical geologist. 



The shifting caused by any elevation of land near the water or 

 poles is very slight, so that the effect of the water displaced is 

 up to about the fifth degree of latitude as great or greater than 

 that caused directly by the movement ol the land. From this it 

 is apparent that near the equator a submarine movement may 

 act on the pole in a contrary direction to that exercised by a 

 similar movement nearer 45° lat. As about one-eleventh of the 

 globe is included between the latitudes 5° N. and 5° S. the 

 effects of the movements here are specially worthy of con- 

 sideration. 



The effects of the drying up of an ancient Caspian Sea was 

 taken as an illustration of the points brought forward. The loss 

 of water of double the area of the Caspian evaporating to a depth 

 of about 200 feet would by the lots of weight of water, shift the 

 pole about 166 feet towards the White Sea, but as this water 

 would be so distributed as to cause additional weight along 

 45° 44' long. E. in the southern hemisphere, it would shift the 

 pole sdll further in the same direction, making a total of about 

 176 feet. If there were a Caspian Sea in the south along this 

 line then similar phenomena would cause a movement of 156 feet 

 as against 176 feet in the north. 



On the Source and Functions of Carbons in the Crust of the 

 Earth, by A. J. Mott.— Plants get their carbon from the air, 

 and as carbon deposits in the earth's crust, from the graphite of 

 the Laurentian to the Lignites of the Tertiary, are believed to 

 be derived generally from plants, the origin of those deposits 

 must be looked for in the source of the atmospheric supply. 

 Calculations based on the reports of the Royal Commission on 

 Coal, and other data, show that the average quantity of unoxi- 

 dised carbon of vegetable origin in the earth's crust cannot be 

 ess, and is probably many times greater, than 3,000,000 tons 



per square mile of surface. This is 600 times as much as the 

 atmosphere now contains in the form of carbon-dioxide, and if it 

 had been drawn from an atmosphere originally char^jed with it 

 to this extent, the oxygen liberated in the process would have 

 been twice as much as now exists. As all animal life is 

 destroyed by any considerable change in the constitution of the 

 air; as it was abundant belorethe coal-formation, and as a great 

 part of the carboniferous deposits are of later date, the theory 

 becomes incredible. We are obliged to conclude thit the carbon 

 withdrawn from the air and returned to the ground by plan's, 

 has been annually supplied, and the liberated oxygen regularly 

 removed, and the only rational explanation is found in the 

 hypothesis that the oxygen and carbon are reunited ; in other 

 words, that carbon equal in quantity to the annual deposit is 

 annually burnt underground. 



The objection to this, founded on the small quantity of 

 nitrogen in subterranean gase.s, is readily shown to be invalid. 

 The annual deposit of carbon, which is a measure of the quantity 

 annually burnt underground, is estimated at three cubic miles ; 

 the estimate being based on the annual produce and the known 

 facts concerning its destination. 



It is shown that by this p'Ocess of oxidation and its physical 

 consequences, the heat developed internally is probably equal to 

 the annual loss, and that the earth, therefore, is not cooling. 

 The extent of geological change thus accounted for is alto 

 considered, and the quantitative deductions are compared with 

 known facts. It is conclu led finally that the carboniferous 

 deposits now existing can only be accounted for on the supposi- 

 tion of previous similar deposits, and consequently that nothing 

 is known at present as to the origin ol vegetable life, or 

 concerning any period before it existed on the earth. 



On the Occurrence of Pehbles in Carboniferous Shales in West- 

 moreland, by G. A. Lcbour. — This was merely a note of occur- 

 rence of rounded and subangular pebbles of quartz or quartzite 

 (which were exhibited) in a bed of carboniferous sh'.le in Angill, 

 Westmoreland. The pebbles were "all of the same character, and 

 were probably derived from some of the Lake District rocks and 

 not from veins. 



Notes on the A^e of the Chr<iot Rocks, by C;. A. Lebour, 

 F.G.S. — The Cheviot Hills consist of porphyrites, passing 

 into granite and syenite ; ashes and doleritic rocks also occur. 

 These igneous rocks are newer than the Silurians, on the 

 denuded upturned edges of which they re>t ; they are okler 

 than the lowest carboniferous (or tuedi.an) beds of Northumber- 

 land, for these rocks are in part composed of porphynte pebbles. 

 This evidence fixes the age of the mass of the Cheviots as 

 Devonian, or thereabouts. The author showed that on the 

 south side of the Cheviots, near the head of Rrdewater, there 

 are vesicular dolerites breaking through the tuedian beds ; else- 

 where (as in Punchestown Burn) there are doleritic breccias 

 Coniaining fragments of porph)ritic and lower carboniferous 

 rocks. Wc thus have evidence, in the Cheviot range, of rocks 

 of probably Devonian, tuedian, and Bcrnician age, belonging to 

 the same eruptive centre. 



SECTION D.— Biology. 



Department of Anatomy and Physiology. 



Address to the Department by Prof. MacAlister, 

 Vice-President. . 



After referring to the strength and independence now pos- 

 sessed by the sciences of animal morphology and physiology, 

 Prof. MacAlister referred to recent important advances in 

 embryohigy. Among researches respecting ihe early formation 

 and primary develo|inenial chani;es m the egg, he alluded to 

 those of E. van beneden, Biitschli, Ihering, and Oscar Hertwig, 

 classified under three heads. (l) What is the method whereby 

 the stimulus to development directly operates oa the egg ; (2) 

 What becomes ol the germinal vesicle ; and (3) In what manner 

 and from what source the directive corpuscles arise, and what 

 function do they serve in the animal economy. The next subject 

 dealt with was the history of the primitive groove of the fertilised 

 egg, as discovered by Dursy, Schiifer, Balt'our, and Rauber. 

 Prof. MacAlister could not but believe that a change had taken 

 place in the position of the embryo on the surface ol the germinal 

 disc in the evolution of vertebrates, and that the primitive grcove 

 was the heirloom of this ancestral change. Coming then to the 

 question of the origin of vertebrate limbs, the address referred to 

 the researches of Ballour and others, showing that the Umbs are 



