Mr. G. Garney.
3 August, 1831.
In proportion to the size of such obstruction there is liability in the crank to break?—Certainly; but the cause which occasions a crank to break is one which cannot be explained on common principles; it frequently happens, as in Steam-boats; and very often in this Carriage, when the power applied to it is not equal to its being broken, the accident occurs, and must be referred to a jar or percussion; the axles are unusually large in consequence.
What is the throw of the crank?—Half the diameter of the stroke of the Engine; eight inches and a half to nine inches.
With a wheel of five feet diameter what is the throw of your crank?—About nine inches.
What is the length of the stroke of your cylinder?—I think 16 to 18 inches; the crank is half that. I may state here, that I have had accidents of breaking the crank two or three times during my experiments; the last crank was broken in consequence of going through some rough stones laid unusually thick. I understand as much as 18 inches deep.
What do you anticipate will be the most frequent accident which will happen to your drawing machines?—I should say the derangement of the pumps is most likely to occur, in consequence of which the Carriage would merely stop.
During the experiments you have been making, have you frequently had your tubes burst?—Very often.
Do you conceive you have remedied the probability of such occurrence?—Yes; the first tubes we used were iron gas tubes, which were not welded, but simply "butted" together; the consequence was, that whenever any great pressure came upon them the seam opened; but from practice and experience we found it necessary to wrap over, or over-lap the, edges, and weld them from end to end; and now we are not subject to those accidents.
What is the diameter of the tubes of your boiler?—We make them from half an inch to two inches the best size. I think, is an inch diameter.
To what pressure per square inch do you prove
