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35.

Of the experiments in the cylindrical tank, 15 and 16 were performed with the elbow [[underlined]] E [[/underlined]], Fig. 17, at the lower end of the 3-inch pipe; No. 17 was performed with this elbow also in place, with the addition of a sheet-iron sleeve in the pipe, to decrease the curvature [[underlined]] at the elbow [[/underlined]]; Nos. 18 and 19 were performed with the tank empty; and the remaining experiments were performed with the fencing, already described, in position.

The tissue paper was usually torn at one end, and not torn completely off. It was only torn completely off, with small charges, in the experiments with the cylindrical tank [[underlined]] empty [[/underlined]]; Nos. 18 and 19. The tissue paper was cut one third across at each end, as already explained, in experiments 15 and 33, inclusive.

The direct-lift impulse-meter was used in experiments 15 to 26 inclusive. In cases in which there was impact of the chamber against the yoke, or pins, at the lower ends of the rods, [[underlined]] R,R, [[/underlined]] Fig. 14, this impulse meter was useless because of the jar. Only in experiments 16 and 22 was there a measurable displacement; the negligible displacements in the other cases being doubtless due to friction. The spring impulse-meter was used only in the last six vacuum experiments.

An inspection of Tables II and III will show that the results, under the same conditions, are in sufficiently close agreement to warrant the comparison of results obtained under various circumstances of firing.

[[underlined]] DISCUSSION OF RESULTS  [/underlined]].

1. There is a general tendency for the velocities in vacuo to be larger than those in air, for the same length of chamber, [[underlined]] 1 [[/underlined]], and