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278 [[image]] In one or two cases, a whirl wind was produced in the use of the heated plate which extended downwards from the mouth of the pipe to the distance of 8 inches. Also in all the arrangements, a whirling motion was produced occasionally sometimes in one direction and sometimes in the other. The whirl was an accidental effect either of the unequal [[strikeout]] action of the air in its approach on different sides to the excs, or in its oblique action on the substances thrown into to the currents to reach their direction. The draft was not sufficiently grat to produce very well marked effects; we propose to repeat the experiment with a blowing machine. [[short squiggly line]] April 3rd Accompanied Mr Espy to Rider's Machine shop in order to observe the effect produced by a centrifugal blowing machine. The draft was quite powerful through the axis of a stove pipe. Probably about equal [[strikeout]] in pressure of half an inch of mercury. [[image]] [[end page]] [[start page]] 279 [[piece of paper pasted onto notebook]] Smithsonian Inst March 29th 1852 My Dear Miss Dix [[image of drawing]]