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which sponges are to be hung for imbibing its moisture,and in the bottom of which a cock is to be fixed for oc-casionally letting off the water that drops from the spon-ges. I apprehend the intention may be more effectuallyanswered, by making the air vessel of a considerable heightabove the surface of the water : for though the air at thebottom is necessarily loaded with moisture, yet in risingto the height of four or five feet, so much of the waterseparates and falls down, as to leave the air seemingly ossufficient dryness. The vessel might be made as high asthe pipe itself: nor would this large size be of any incon-venience in regard to the blast, for as soon as it is filledwith air of a certain density, the blast will continue of thesame force as from a small vessel. The joints should bewell secured to prevent the escape of any air throughthem : the stone for receiving the dash of water, shouldbe placed near as much below the level of where thewater runs off, as the gage is expected to rife ; and the pipeshould reach as low as within five or six inches of thestone. It would perhaps be of some advantage to havethe surface of the stone a little concave, so as to occasionthe watery drops to be rather dashed backwards towardsthe stream, than thrown upwards through the cavity ofthe vessel.

III. Experiments of air faffing down through pipes withfalling water.

Water running through a crane.

In the running of water through a siphon or commoncrane, when the sucking pipe on the long leg of thecrane was stopt, the water, as it issued from the extremity,filled the bore : on opening the sucking pipe, the columnof water appeared less than the bore.

Pp 2

Judging