July 4, 1901] 



NATURE 



241 



In recent years many amateurs have participated in systematic 

 observations of the Perseids, and the number of doubly observed 

 meteors has been greatly augmented. In July, 1900, three early 

 Perseids were recorded in duplicate and gave heights and radiants 

 as follow : — 



July 19 



Height at begii 



Radiant. 



17 + 50 

 24+52 

 30 + 52 



a sufficient 

 radiant on 



In time it will be possible to accumulate 

 number of these observations to assign the 

 every night during the last half of July. There will certainly 

 be small errors in the individual positions, and they will not 

 absolutely agree in showing the regular progression of the 

 radiant eastwards, but the mean places derived from a consider- 

 able number of meteors will no doubt yield very satisfactory 

 results. 



In previous years much has been effected at the July and 

 August epoch, but still more remains to be done. Photography, 

 of which so much was expected, has achieved little, but its 

 possibilities are great and it may ultimately prove as successf\d 

 in this department as it has done in several others. The 

 fact, however, remains that we are still mainly dependent upon 

 eye observations, though they are no more than rough and 

 hurried estimates of position, and scarcely capable of being use- 

 fully employed in any refined or critical investigations of the 

 subject. But with care and long practice it is possible to 

 acquire a degree of accuracy which would hardly have been 

 credited, and we must not forget that some important conclu- 

 sions have been safely based on rough eye observations. The 

 virtual identity of comets and meteors has been established, the 

 heights and velocities of meteors approximately determined, while 

 the positions of some hundreds of radiants have been ascertained 

 with fair accuracy. Features such as the motion of the Perseid 

 centre, the stationary aspect of the Orionid and certain other 

 radiants, and the large area of radiation of the meteors of Biela's 

 comet, have been demonstrated. But much additional data are 

 required, and as photography has hitherto supplied very meagre 

 results, observers have to fall back upon the old-time method as 

 vastly more productive if far less precise. It will be remembered 

 that some years ago it was thought that the photographic plate 

 would soon supersede the observer in regard to the delineation 

 of planetary detail, but this idea has not been realised. It is 

 true that planetary and meteoric observations are different and 

 therefore not -strictly comparable, but we have gained enough 

 experience to see that the meteoric observer is in no immediate 

 danger of being displaced. W. F. Denning. 



THE "EDISON" STORAGE CELL. 



r^ONSIDERABLE interest was aroused a short time ago by 

 ^-' the announcement that Mr. Edison had invented a new 

 secondary battery. As was only to be expected of a rumour, 

 circulated mainly by the lay Press and dealing with one of Mr. 

 Edison's inventions, it was said that the new cell was going to 

 revolutionise entirely the electrical storage of energy and to 

 throw open to the undisputed control of the electrical engineer 

 the much-desired field of motor-car work. Fortunately, in this 

 case, even if rumour has been somewhat extravagant, it has not 

 been without foundation. Mr. Edison has in reality invented a 

 new storage cell which is novel in principle and full of promise. 

 A full description of the invention was given by Dr. A. E. 

 Kennelly at the annual meeting of the American Institute of 

 Electrical Engineers on May 21, and we are able, from a re- 

 print of this paper which appeared in the Electrical Review of 

 New York (May 25), to obtain data for a preliminary considera- 

 tion of the merits of the cell. 



Mr. Edison — like many other inventors, only with more 

 success than is met with by most — set out with the object of 

 devising a cell which should possess the following merits : — • 

 (l) Absence of deterioration by work, (2) large storage capacity 

 per unit of mass, (3) capability of being rapidly charged and 

 discharged, (4) ability to withstand careless treatment, and 

 (5) inexpensiveness. 



It will be best first to describe the solution that Mr. 

 Edison has offered, and then to examine, as far as is possible 

 from the information available, to how great a degree the above 

 requirements are satisfied. The problem thus clearly stated by 



Dr. Kennelly is one which has been long realised by all in- 

 terested in the matter, and by none, perhaps, more than by the 

 makers and users of motor-cars. The one great difficulty in the 

 construction of a good electrical motor-car, or in the equipment 

 of a satisfactory system of accumulator tramways, has been the 

 want of a suitable storage cell. If this were only provided, we 

 have been told, then the electrical motor-car would know no 

 rival, seeing that it would be free from all the objectionable 

 noise and smell incidental to petroleum automobiles. It is, 

 therefore, most earnestly to be hoped that the new Edison cell 

 will do all that is claimed for it. 



The cell is an entirely new departure in storage batteries, the 

 materials used in its construction being iron and nickel oxide. 

 The active material of the negative plate of the cell consists of 

 iron, that of the positive plate of a superoxide of nickel believed 

 to have the formula NiO.,. Thus the iron corresponds to the 

 spongy lead and the oxide of nickel to the lead peroxide of a 

 lead accumulator. The electrolyte used is an aqueous solution 

 containing about 20 per cent, by weight of caustic potash. The 

 E. M.F. of this combination — iron, potassium hydrate, nickel 

 superoxide — is about I '5 volts when fully charged and falls to 

 about I '15 at the end of the useful discharge. At the end of 

 the discharge the iron is oxidised and the nickel oxide reduced ; 

 the charging process carries back the oxygen through the 

 potash solution from the iron to the nickel plate, the energy 

 being thus stored in the reduced iron, which, though unaffected 

 by the solution in ordinary circumstances, is reoxidised when 

 the cell is allowed to discharge. The solution, therefore, does 



NO. 1653, VOL. 64] 



Fig. I. — Grids and Briquettes, Edison Storage Battery. (From The 

 Electro-Chemist and Metallurgist.) 



not apparently enter at all into the chemical action which takes 

 place, but only serves as a vehicle for transporting oxygen from 

 the one plate to the other ; this is of considerable advantage, as 

 it allows a minimum of solution to be employed. 



The mechanical construction of the two plates is identical, 

 the only difference between them being in the active material 

 used. The plates are made of comparatively thin sheets of 

 steel (a little more than 0-5 mm. thick), out of which rectangular 

 holes or "windows" are stamped. In the plates exhibited 

 there were three rows of eight such windows, these holes occu- 

 pying, of course, by far the greater proportion of the area, the 

 steel framework being merely sufficient for strength and rigidity. 

 Into these holes are fitted small nickel-plated steel boxes con- 

 taining the active material in the form of closely consolidated 

 briquettes. These boxes are somewhat thicker than the grid, 

 being about 2 '5 mm. thick in the finished plate, and are perfor- 

 ated, back and front, with numerous small holes to allow access 

 of the electrolyte to the active material. The general appear- 

 ance of the grid and briquettes can be seen from Fig. i. 



The positive briquettes are made by mixing a finely divided 

 compound of iron with a nearly equal volume of thin flakes of 

 graphite, the graphite being added to increase ihe conductivity 

 of the briquettes. The mixture is pressed in a mould under an 

 hydraulic pressure of about two tons per square inch. The 

 surface area of each face of the briquette is about 3 inches by 

 h inch. The negative briquettes are made in a precisely similar 



