PHILOSOPHICAL TRANSACTIONS. 



507 



VOL. LXXVIII.J 



municated to the electrometer, while the position of the apparatus is such that 

 the cross-piece gii touches the 2 pins; a very few turns will render it perceptible. 

 But here, as well as in the common doubler, the effect is rendered uncertain by 

 the condition, that the communicated electricity must be strong enough to de- 

 stroy and predominate over any other electricity the plates may possess. It 

 scarcely need be observed, that if this difficulty should hereafter be removed, the 

 instrument will have great advantages as a multiplier of electricity in the facility 

 of its use, the very speedy manner of its operation, and the unequivocal nature 

 of its results. 



XXVII, Abstract of a Register of the Barometer, Thermometer, and Rain, at 

 Lyndon in Rutland^ with the Rain in Hampshire and Surrey, in 1787» Also 

 some Account of the Annual Growth of Trees. By T. Barker, Esq. p. 408. 



On the annual growth of trees. 

 Oaks, 



Girth. Girth. Bate. Girth, Rate. 



In. In. In. In. In. 



1 1772 19 1787 41 1.5 



2 1758 13 1772 33 1.4 1787 55| 1.5 



3 1758 18| 1772 40j 1.6 1787 58 1.2 



3t2 



