Clearance of Engine Cylinder Question: How may the clearance of an engine cylinder be determined?-E. F. Answer: One easy method is to disconnect the valve, and block in midposition to cover the ports; also putty up wherever necessary to prevent leakage at either the valve or the piston. Next, place the engine on the center; and by means of the indicator pipe, fill the clearance volume with water by pailfuls, weighing each pailful before pouring in, and the amount left over in the last pailful. Then, knowing the weight of the pail, the total weight of water poured in may be found. Dividing this weight (in pounds) by 62.5, will give you the number of cubic feet in the clearance volume. Dividing this by the volume of the piston. displacement will give the clearance percentage. Pitch of Propeller Question: What is an approximate rule for finding the pitch of a propeller?—H. L. B. Answer: Find the place on the propeller blade where the slope of the face is 45°, or where it is equally inclined to the shaft and to the transverse direction. A circumference taken through this point will be equal in length to the pitch. Starting near the shaft of the propeller, the inclination to the longitudinal is small; but it increases towards the tip of the blade, passing at some point through the value 45°. Let the radius of this point be r. Then, Pitch 2 ir 6.2832 r. In this approximate way it is necessary to make practically but one measurement. Mention Technical World Magazine SOLIDED THUMB TACKS IN COLORS ARE THE HANDIEST AND MOST ATTRACTIVE FASTENING TACKS THUMB As a Practical Book for Practical Men Spangenberg's Book Ranks First Spangenberg's Steam and Electrical Engineering is a complete library covering the subject in all its various branches and contains 672 pages. Bound in Silk Cloth. Size 6x9. 672 pages. 648 Illustrations. $3.50 is the price, and it is sold with the understanding that it may be returned if not satisfactory, and your money will refunded im- TACKS THUMB TACKS 20th CENTURY SOAP, a purely vegetable oil soap, containing no lye, but cleaning by the penetrating nature of its oils. Good for engineers, electricians, chemists, etc., it thoroughly removes all stains, such as rust, grease and oil, either from the hands or clothing, without injuring in the slightest. Also unsurpassed as a DRILLING SOAP. HAS NO EQUAL FOR AUTOMOBILES. For cleaning floors and walls, especially hard wood, it is invaluable. Does not injure the polish, but adds to the lustre. If your dealer does not keep it, send us his name and address and we will send you a large can free. HOFFHEIMER SOAP COMPANY, 168 East Jackson Boulevard, CHICAGO Renshaw Bldg., PITTSBURG, PA. Eastern Office, No. 1 Madison Square, NEW YORK. Mention Technical World Magazine CONSULTING DEPARTMENT-(Continued) Question: What is angular velocity?— B. L. C. Answer: It is a term used to denote the angle through which any radius of a body turns in a second; or the rate (expressed in feet per second) at which a point in the body having a radius equal to unity is moving. If the angular velocity is given in revolutions per minute, the linear velocity can be found by the formula: Linear Velocity = 21 rn. A radian is equal to an arc whose length is equal to the radius of the circle. From this definition it is easy to see that there are 2 radians in one complete circle. Therefore, Radians per minute will be 21 times Revolutions per minute. But from the above we see that linear velocity 2 rn, in which n is the revolutions per minute, and r is the radius. Substituting 2 n for "Radians per minute" in this equation, we get Linear Velocity times Radians per minute. = Effect of Centrifugal Force Question: Is it correct to state that centrifugal force tends to throw a revolving body away from the center?-R. N. W. Answer: It is not, strictly speaking, correct, as no such force acts on the body. If the centripetal force be destroyed, the centrifugal force is destroyed at the same time, and the body goes off at a tangent instead of radially. The above form of statement is, however, a popular and convenient way to express what appears to be true, just as we say "the sun rises," to express an appearance, whereas the sun in fact does not move. Thus, the common expression, "The centrifugal force caused the fly-wheel to burst," strictly means that the arms of the wheel were not sufficiently strong to compel the rim to move in a circle, and in their effort to do it the arms were broken. But the cause of the breakage is as well understood from the common expression as from a scientific explanation of it. Question: G. L. F. Solicited Setting Corliss Valves How are Corliss valves set?Answer: On the back bonnet side of Mention Technical World Magazine ATENTS "During the past ten years Mr. Shepherd, of Shepherd & HALLWOOD CASH REGISTER CO. Patent Lawyers Mr. Parker on November 1, 1903, resigned his position as an Mention Technical IVorld Magazine |