On the 14th of August the following experiment was made. The weather being perfectly calm, an empty bottle, corked very tight, was sent down 20 fathoms, and it was drawn up still empty. It was then sent down again 35 fathoms, when the weight of the water having forced in the cork, it was drawn up full; the water it contained was immediately tried by the thermometer, and found to be 70, which was six degrees colder than at the surface; the lead and bottle were visible, but not very distinctly so, at the depth of 12 fathoms; but, when only 7 fathoms deep, they were perfectly seen from the ship. This experiment was thus repeated September 11th, when we were in soundings of 18 fathoms. A keg was previously prepared with a valve at each end, one opening inward, the other outward; this was sent to the bottom in expectation that by the valves being both open when going down, and both shut when coming up, it would keep within it the water received at bottom. The upper valve performed its office well, but the under one did not shut quite close, so that much of the water was lost in hauling it up the ship's side. As the water in the keg's passage upwards could not enter at the top, it was concluded that what water remained in it was of that near the ground; and, on trying this by the thermometer, it was found to be 58, which was 12 degrees colder than at the surface.

[This last Journal was obligingly kept for me by Mr. J. Williams, my fellow-passenger in the London Packet, who made all the experiments with great exactness.]

1598. TO JAN INGENHOUSZ1

ON THE CAUSES AND CURE OF SMOKY CHIMNEYS

DEAR FRIEND,

(L. L.)

At Sea, August 28, 1785

In one of your Letters, a little before I left France, you desire me to give you in Writing my Thoughts upon the Construction and Use of Chimneys, a Subject you had sometimes heard me touch upon in Conversation. I embrace willingly

1 This letter, which has been published in a separate pamphlet, both in England and America, first appeared in the Transactions of The American Philosophical Society, Vol. II, p. 1 (1786), in which it was read October 21st, 1785.- ED.

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bound from Philadelphia to France, in October and November, 1776. mometer; with other Remarks made on board the Reprisal, Captain Wickes,