3. The double Bellows were bound fast to a Frame, at the upper Part of the Iron Nose, and at the lower Handle, in order the more commodiously to work them. And that the upper Half of the double Bellows may duly rise and fall, in order to cause a constant Stream of Air; (besides the usual contracting spiral Springs within side) several flat Weights of Lead must be layed on the upper Part of the Bellows, near the Handle, with a Hole in their Middle, to fix them on an upright Iron Pin fastened on the Bellows: That by this Means the Weights may the more commodiously be put on or taken off. For, according to the different Depths of the Liquor in the Still, so will the Force of the included Air, against the upper Board of the Bellows, be more or less. Thus, supposing the Depth of the Water in the Still to be twelve Inches; from the Surface of the depressed Water in the Air-Box; then the Pressure of the included Air against the upper Part of the Bellows, will be equal to that of a Body of Water a Foot deep, and as broad as the inner Surface of that Board. It will, therefore, be requisite, to add or take off Weights, according to the different Depths of the Water in the Still, at different Periods of the same Distillation. The Bellows must be proportionable to the Size of the Still, but need not be very large. Wherever the Stills are fixed in Ships, the Air may be conveyed to them from the Bellows, either thro’ a small leathern Pipe, distended with Spiral Coiles of Wyre, or thro’ Bamboo Canes, or broad small wooden Pipes, like hollow fishing Rods. 4. When I first distilled in this ventilating Way, in order to estimate, what the Difference might be in the Quantity distilled, by that or the common Method, I tried both Ways, by receiving the distilled Liquor into a Quarter of a Pint Glass, estimating the Times, by a Pendulum beating Seconds. Where I found, to my Surprise, that sometimes three times more was distilled by Ventilation than by the usual Way: But finding Inequalities in the small Quantities thus distilled, in order the more fully and assuredly to ascertain the true Proportion there was in the two Methods of distilling, I put three Gallons of Water into the Still; and, when it boiled, put on the Still-head, and fixed its Nose to the Worm-tub Pipe; which Tub was full of cold Water. When it had distilled for an Hour, the Receiver was instantly taken away. And on measuring the distilled Water, found it to be two Quarts and 45 cubick Inches by a Glass divided into cubick Inches. And a Gallon containing 282 cubick or solid Inches, this Quantity of distilled Water, which was 186 cubick Inches, is 1/1.5 th Part of a Gallon.