SCIENCE. 



291 



Ohio, the whole constituting the broadest study on the 

 " Great River Age " that has been made. He considers 

 the great lakes as largely valleys of subae'rial erosion, tra- 

 versed by the Grand River which he has worked out. 

 The Ancient buried course of the Niagara, the author 

 considers as interglacial, being formed and closed sub- 

 sequent to the closing of the Dundas Valley. Of course, 

 all this presupposes the action to have been going on 

 when the continent was six hundred feet higher, and 

 from the pot-holes in the New York Harbor, we know it 

 to have had an altitude of at least 900 above the piesent 

 elevation. To perfect the work there remains the discov- 

 ery of the outlet of Lake Ontario, which was not by the 

 Mohawk, as in its valley near Little Falls, it passes 

 over hard rock. Yet Prof. Spencer insinuates, in 

 this paper, that he is on the track of this discovery 

 also, and that the study will be pursued during the com- 

 ing summer. We wish the author every success, and if 

 this ancient outlet be discovered, certainly he will 

 have added much to his already most important discov- 

 ery, and wdl fairly be considered as one of the founders of 

 this new scientific development. 



It must be further stated that the author does not con- 

 sider all the ancient buried rivers now running south- 

 ward, but formerly flowing northward, as having in any 

 way been derived from glacier action, and more recently 

 than the paper, which we are reviewing, a notice by him 

 was read before the American Philosophical Society 

 showing that the Monongahela flowed directly north- 

 ward by the upper Ohio, Beaver, Mahoning and Grand 

 Rivers of Ohio (the last three reversed in Preglacial 

 times) to Lake Erie, thus adding another important trib- 

 utary to the Erie Basin and further changing the physi- 

 cal features of the Continent. 



This paper, which is the first preliminary notice of his 

 ■work on the Great River Age, will do much to draw at- 

 tention to the interesting subject which is destined to 

 have an equal place with Glacial Geology, with the ex- 

 treme views of which it will be found to conflict more or 

 less. 



ON M. C. FAURE'S SECONDARY BATTERY. 



The researches of M. Gaston Plants on the polarization 

 of voltameters leJ to his invention of the secondary cell, 

 composed of two strips of lead immersed in acidulated 

 water. These cells accumulate and, so to speak, store up 

 the electricity passed into them from some outside gene- 

 rator. When the two electrodes are connected with any 

 source of electricity the surfaces of the two strips of lead 

 undergo certain modifications. Thus, the positive pole 

 retains oxygen and becomes covered with a thin coating 

 of peroxide of lead, while the negative pole becomes re- 

 duced to a clean metallic state. 



Now, if the secondary cell is separated from the primary 

 one, we have a veritable voltaic battery, for the symmetry 

 of the poles is upset, and one is ready to give up oxygen 

 and the other eager to receive it. When the poles are 

 connected, an intense electric current is obtained, but it is 

 of short duration. Such a cell, having half a square metre 

 of surface, can store up enough electricity to keep a platin- 

 um wire 1 millim. in diameter and 8 centims. long, red-hot 

 for ten minutes. M. Plante has succeeded in increasing 

 the duration of the current by alternately charging and 

 discharging the cell, so as alternately to form layers of 

 reduced metal and peroxide of lead on the surface of the 

 strip. It was seen that this cell would afford an excellent 

 means for the conveyance of electricity from place to place, 

 the great drawback, however, being that the storing capa- 

 city was not sufficient as compared with the weight and 

 size of the cell. This difficulty has now been overcome 

 by M. Faure: the cell as he has improved it is made in 

 the following manner : 



The two strips of lead are separately covered with 

 minium or some other insoluble oxide of lead, then covered 

 with an envelope of felt, firmly attached by rivets of lead. 

 These two electrodes are then placed near each other in 

 water acidulated with sulphuric acid, as in the Plantd cell. 



The cell is then attached to a battery so as to allow a cur- 

 rent of electricity to pass through it, and the minium is 

 thereby reduced to metallic spongy lead on the negative 

 pole, and oxidised to peroxide of lead on the positive pole ; 

 when the cell is discharged the reduced lead becomes 

 oxidised, and the peroxide of lead is reduced until the cell 

 becomes inert. 



The improvement consists, as will be seen, in substitut- 

 ing for strips of lead masses of spongy lead ; for, in the 

 Plante cell, the action is restricted to the surface, while in 

 Faure's modification the action is almost unlimited. A bat- 

 tery composed of Faure's cells, and weighing 150 lbs., is 

 capable of storing up a quantity of electricity equivalent to 

 one-horse power during one hour, and calculations based 

 on facts on thermal chemistry shows that this weight could 

 be greatly decreased. A battery of 24 cells, each weighing 

 14 lbs., will keep a strip of platinum ^ths of an inch wide, 

 i-32nd of an inch thick, and 9 feet 10 ins. long, red hot for 

 a long time. 



The loss resulting from the charging and discharging of 

 this battery is not great: for example, if a certain quantity 

 of energy is expended in charging the cells, 80 per cent of 

 that energy can be reproduced by the electricity resulting 

 from the discharge of the cells ; moreover, the battery can be 

 carried from one place to another without injury. A battery 

 was lately charged in Paris, then taken to Brussels, where 

 it was used the next day without recharging. The cost is also 

 said to be very low. A quantity of electricity can be pro- 

 duced, stored, and delivered at any distance within 3 miles 

 of the works for i^d. Therefore these batteries may be- 

 come useful in producing the electric light in private houses. 

 A 1250 horse-power engine, working dynamo machines giv- 

 ing a continuous current, will in one hour produce 1000 

 horse-power of effective electricity, that is to say 80 per 

 cent of the initial force. The cost of the machines, estab- 

 lishment, and construction will not be more than ,£40,000, 

 and the quantity of coal burnt will be 2 lbs. per hour per 

 effective horse-power, which will cost (say) }4d. The ap- 

 paratus necessary to store up the force of 1000 horses for 

 twenty-four hours will cost .£48,000, and will weigh 1500 

 tons. This price and these weights may become much less 

 after a time. The expense for wages and repairs will be 

 less than ^d. per hour per horse-power, which would be 

 £24 per day. or £8800 a year; thus the total cost of one- 

 horse-power for an hour stored up at the works is ^d. 

 Allowing that the carriage will cost as much as the pro- 

 duction and storing, we have what is stated above, viz., 

 that the total cost within 3 miles of the works is i^d. 

 per horse-power per hour. This quantity of electricity will 

 produce a light, according to the amount of division, 

 equivalent to from 5 to 30 gas burners, which is much 

 cheaper than gas. — Chemical News. 



MICROSCOPY. 



We offer the following notes culled from the pages o( 

 the Journal of the Royal Microscopic Society : — 



A singular species of Ncarus is described by A. D. 

 Michael, found by him at Land's End, England. It 

 belongs to the genus Dermaleichus (Koch) Analges 

 (Nitsch) but does not fit into any of the five genera, or 

 sub-genera, into which Robins has divided the group. 

 The leading feature in this curious creature was that the 

 male had the left leg of the second pair conspicuously 

 larger than its fellow on the right side, had a totally dif- 

 ferent tarsus, and supported by a different and more pow- 

 erful epimeral and sternal arrangement. This de- 

 formity makes this species entirely different to any other 

 Ncarus. 



Haustein has observed in the central cells of chara, 

 chlorophyll-bodies containing starch which could not be 

 regarded as the product of assimilation. C. Dehnecke 

 has now investigated a number of similar instances, in 

 which the starch contained within the chlorophyll-grains 

 appears not to serve the purpose of immediate assimila- 

 tion, but to be stored up as a reserve material. 



A new stereoscopic eye piece has been arranged by 

 Professor E. Abbe. The special feature of this instrument 



