486 Effects of Conical Ajutages, [Book V.
of a tapering form to them, or by enlarging the ends themselves. Of anumber of Experiments, the following will be sufficient for our presentpurpose. In two of the tubes (Nos. 211 and 212) the exhausting pipe didnot protrude into the blowing one : in No. 213 it did. As it is difficult tokeep up a strong blast from the lungs through a pipe so large in the boreas half an inch, No. 211 was made of quarter-ineh tubing, and No. 212 offive-sixteenths. The blowing tube of No. 213 was seven-sixteenths, andthe exhausting one three-sixteenths, and all were made of lead. Besidesthe tubes just named we prepared a dozen conical ones, nine inches long,the small ends one-quarter inch bore, and the large ones varying fromthree-fourths to 2J inches. They were made of tin plate, the seams werelapped, and no particular care was taken in their formation. From nu-merous trials with them in a variety of ways, we obtained the best resultswith two, one of which was 1^ inches at the large end, and the other seven-eighths. But of these the latter, marked C in the cut, generally caused thewater to rise highest in the exhausting tube.
The discharging end of No. 211 extended lj inches from the joint,and the opposite end 2J inches. When blownthrough in the direction of the arrow, part ofthe current descended through the water, butwhen the conical pipe C was held close to thedischarging end the liquid rose in the verticalpipe 9J inches. A quarter of an inch was nextcut off the discharging end and C again ap-plied, when the water rose 12 inches. Theend was next remered out with the taperedprong of a file, when the water rose (withoutC) 11 inches. Another portion was next cutoff, leaving only half an inch in front of thejoint, and the end swelled out as before, uponwhich the rise was 7 J inches ; but when Gwas applied the water rose 17J inches.
In all the trials with C it was necessary, in Order to obtain the bestresults, that its axis should coincide with that of the blowing tube ; other-wise the current of air is deflected in its passage. The length of theblowing end of the tube should be no more than what is necessary to givea straight direction to the current. If longer than this, the velocity andstrength of the blast is unnecessarily diminished by friction against theprolonged sides. The blowing tube should also be straight and smoothwithin; for the energy of the blast is less diminished in passing through astraight than through a crooked channel—through a smoothly polishedtube than through one whose interior is marked with asperities. Moreover,dints or bruises in a pipe produce counter currents, and materially diminishthe ascent of the liquid. In small tubes, the end received into the mouthmight be enlarged or cut obliquely to facilitate the entrance of the air;for if the fluid be retarded in its entrance, part of the force exerted by thelungs is uselessly expended. It is immaterial in what position the blowingtube is used.
In No. 212 the blowing tube was jointed to the exhausting one at an angleof 20°. The part in advance of the joint was 1|[ inches. Upon trial, the liquidrose seven inches. The tube D was applied, (its small end being enlargedto five-sixteenths) and the water rose nine inches. The tube was thenswelled out by the prong of a file until its orifice was seven-sixteenths ofan inch, when the rise was 10J inches. D was then applied, its end en-tering the other, and the water rose 18 inches. Previous to this trial D
No. 211.
No. 212. No. 213.