VOL. XLIX.] PHILOSOPHICAL TRANSACTIONS. 589 



face of the mass; and that, by that means they must be equally electrified with 

 the mass, that is, they must be covered with the electrical fluid to as great a 

 distance from their superficies as the mass is covered ; which must always be in 

 proportion to the state of activity of the electrical fluid. In which state, when 

 they have passed the surrounding fluid, they must be repelled by it; and also 

 repel each other; and if each particle of vapour, and its surrounding fluid, oc- 

 cupy a greater space than the same weight of air, they must be fitted to ascend 

 till they come in equilibrium with the upper and rarer part of the atmosphere; 

 where they must float, till their specific gravity is altered. As it is very difficult 

 to assign the magnitude of each particle of vapour and exhalation, and that of 

 the surrounding fluid; and to show that both, taken together, occupy a greater 

 portion of space than the same weight of air; we can only apply to experiment, 

 to show that it is possible that it may be so; and that will show, that in all pro- 

 bability it is so; since it is evident, that every particle must be endued with a 

 portion of this electrical fire or fluid; and that there is not any other sufficient 

 cause assigned for their ascending. 



It is evident, that on electrifying any light matter, such as down, or the 

 downy parts of feathers, their specific gravity is much lessened; and that, by 

 holding another electrified body under them, .they may be driven upwards at 

 pleasure. It is also evident, from experiment, that the more you divide the parts 

 of such bodies, the more of their specific gravity they will lose by being elec- 

 trified ; and by dividing them into very minute parts, that they ascend to a con- 

 siderable height after they are electrified. Hence he thinks it highly probable, 

 that the exceedingly small particles of vapour and exhalation may be, and are, 

 sufficiently electrified, to render them specifically lighter than the lower air; and 

 that they do ascend by that means. And that they will ascend proportionally 

 higher, as the surrounding fluid is proportionally greater than the particle which 

 is carried up. 



Mr. E. then endeavours to show that the ascent and descent of vapour and 

 exhalation, attended by this fire, is the principal cause of all our winds. It 

 being admitted that wind is only air put into motion, many have been the con- 

 jectures how that motion is caused. Among which, the motion of the earth, 

 and the air's being rarefied by the sun, seem to stand first. The trade winds 

 being most regular, and occupying a considerable part of the globe, it has been 

 thought proper first to account for them, from the afore-mentioned causes. But 

 he thinks that these causes, by themselves, are not sufficient for the motion of 

 those winds, and much less so for the irregular motion of all the other winds. 

 If the apparent motion of the air was occasioned by the diurnal revolution of 

 the earth from west to east, by the air's being left behind, the motion must be 

 found more regular, and very different from what it is; for in that case the 



