would allow. The flow of air was then so large that the cylinder of gauze M produced too much choking to give a convenient reading of the oil-gauge, and it had to be removed, so that the choking was then supplied by the .tube connecting E and 1ST ( fig. 2) and a very small piece of cotton-wool in 1ST. Even under these conditions the readings of the oil-gauge were fairly steady with this nozzle. The first reading of pi was of course not very low in this case, but it is seen to lie well on the

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... izontal portion of the curve. The result for the nozzle of larger diameter is seen to be practically the same as that for a smaller one of the same shape.