VOL. XV.] PHILOSOPHICAL TRANSACTIONS. 157 



humour, was in the 43d year of his age seized with a great pain over all his 

 right arm; a great heat, and redness in his right hand; and a pricking in the 

 point of the fore-finger, on which there appeared a small speck, as if a little 

 thorn had run in; and supposing it such, he opened it, on which the blood 

 spun out in a violent but small stream ; after spending its violence, it would 

 cease for a while, and only drop, and then spring out with violence again; con- 

 tinuing thus for 24 hours, till at last he fainted away, and then the blood 

 staunched of itself, and his pains left him : from that time during his whole 

 life, which continued 12 years, he was frequently troubled with like fits; seldom 

 having a respite of 2 months, and they never returned oftener than in 3 weeks : 

 he rarely bled less than a pottle at a time; the oftener the fit came, the less he 

 bled; and the more rarely it assaulted him, he bled the more; whenever they 

 endeavoured to staunch the blood, it raised most exquisite tortures in his arm ; 

 no remedies proved in the least effectual : he had no other distemper that 

 troubled him ; neither season nor weather affected him : he had no outward 

 accident that at first brought on the bleeding : drinking more than ordinary made 

 him more apt to bleed : these frequent fits brought him at last very low, inso- 

 much, that towards his latter end he bled but little, and that too but like 

 diluted water. He died at last of this distemper. 



On the Changes of Weather from the Alterations in the Weight of the At- 

 mosphere, &c. By Dr. Garden of Aberdeen. Communicated to the Phil. 

 Sac. of Oxford, by the Rev. Dr. Middleton, Provost of the King's College 

 in Aberdeen. N° 171, p. QQl. 



The air agrees with all other fluids in this, that it gravitates; and it has this 

 peculiar property, which is not so much observed in other fluids, that its spe- 

 cific gravity is not always the same. Now, according to the rules of the equi- 

 librium of fluids, every fluid specifically lighter than another, will ascend and 

 emerge above it; and every fluid specifically heavier, will descend and subside 

 below it. Now there is some certain proportion between the specific gravities 

 of the fluid of air, and of that which ascends in vapours, and falls down again 

 into rain ; and if this proportion were always the same, it is like we should 

 have no commixture of these fluids, but the vapours would either always float 

 above or always remain below. But this proportion of their specific gravity is 

 frequently changed; for it is known that water when warm is lighter than when 

 it is cold; and yet perhaps the small particles of it, if figured according to Des- 

 cartes' conjecture, are more capable of ascending in vapours in frost, than at 

 another season, as being more extended, and so having a larger portion of the 

 fluid of air to sustain them ; and the daily observations of the different heights 



