Mr. J. N. Lockyer on the recent Solar Discoveries. 61 



Table VIII. 



Equivalent number 

 Potential. of Grove cells. 



Five Grove cells .... 3 5 



Forty secondary cells . . 23 38*3 



Do. with five Grove cells . 26 43*3 



Now, since the electromotive force of the forty secondary celli 

 in series is represented by 23, that of live cells will be 2 - 875; 

 and as the force of the five Grove cells is expressed by 3, we see 

 that the force of each set of five secondary couples is 95 '83, or 

 nearly 96 per cent, of that of the exciting battery, a result which 

 can scarcely be greatly surpassed. An experiment was made to 

 test the usefulness of this form of battery for telegraphic pur- 

 poses. The discharge was sent through 19,000 B.A. units, or 

 more than twice the resistance of the Atlantic cable, and was 

 received at an indicator such as is employed only to test the 

 continuity of telegraph wires, and which is a comparatively 

 coarse instrument. The deflection of the needle when contact 

 was first made was 35°, and at the end of one minute, the con- 

 tact having been continued during that time, 20°; whereas the 

 five Grove cells could of themselves produce but a very feeble 

 motion of the needle, of 2° or 3° only. An excitation of five 

 seconds' duration appeared to completely restore to the secondary 

 battery its original power. 



17. There is one disadvantage attending the use of the car- 

 bonate-of-sodium solution in secondary batteries, viz. the efflo- 

 rescence on the plates and cells. Many different substances, 

 such as shellac in alcohol, oil, lard, and black enamel varnish, 

 have been tried, but sooner or later the crystals of the car- 

 bonate creep either under or over the varnish. Perhaps hot 

 paraffine poured into the top of the cells when the battery is 

 first made, and, after cooling, a hole bored to allow of the 

 escape of any gas generated, might answer the purpose of check- 

 ing the efflorescence. 



Hadham House, Upper Clapton, 

 December 13, 1869. 



IX. Reply to some Remarks of Father Secchi on the recent Solar 

 Discoveries. By J. Norman Lockyer, F.R.S.* 



THAT portion of a recent note (communicated to the Royal 

 Society and printed in the Comptes Rendus of the 12th of 

 July) which had reference to Father Secchi's observations, had 



* Communicated bv the Author. 



