On supporting science journalism
If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.
Hints to Correspondence Names and Address must accompany all letters, or no attention will be paid thereto. This is for our information and for publication. References to former articles or answers should give date or paper and page or number of question. Inquiries not answered in reasonable time should be repeated; correspondents will bear in mind that some answers require not a little research, and, though we endeavor to reply to all either by letter or in this department. each must take his turn. Buyers wishing to purchase any article not advertised in our columns will be furnished with addresses of houses manufacturing or carrying the same. Special Written Information on matters of personal rather than general interest cannot be expected without remuneration. Scientific American Supplement referred to may be had at the office. Price 10 cents each. Books referred to promptly supplied on receipt of price. Minerals sent for examination should be distinctly marked or labeled. (6538) C. A. G. writes : I am making a chime of three whistles, the bells to be of 2 inches brass tubing, J.B inch thick, the longest tube or bell to be 8 inches. The cap piece will extend into top of bell about inch, of course shortening air column that amount. The longest bell being the key note. I wish the others to be higher in pitch, and all to range as do, me, sol, or as in key of . C major, C, E, and G. I wish to know of what length to make each of the other two bells, and also about what size opening should I give the steam vent under the bells with steam pressure of 150 pounds. A. The making of a chime whistle is a matter of experiment until the relative conditions are found. Make the low tone whistle first, then use a sliding plug in the bell for regulating the tones of the other whistles. The steam slot should be about one-fiftieth of an inch opening. (6539) J. H. M. writes: I have two nests of boilers, six in a nest, and what is the horse power of each boiler. or what is the horse power of 12 boilers ? Each boiler is 47 feet 7 inches in length by 30 inches diameter. Fire box 16 feet in width by 6 feet in back. What is the cause of a set of boilers foaming when the fires are kept all the same heat, bridge wall the same height, and water enough going in boiler con-tinu lly ? A. If your boilers are plain cylinder boilers, without flues, they are 19 horse power each, or 228 horse power for the 12. The foaming IS probably caused by driving too hard, or by bad water. (6540) W. S. M. writes: I purpose to lay some old 2).2 inch and 3 inch pipe along both sides of the shop about 7 feet from the floor for heating purposes. Engine exhaust 4 inches. My idea is to connect with two 3 inch pipes and go down each side, which is 78 feet, and return with 2 inch pipes; this will use all we have got, but will return the second time if you think feasible. Or would it be better to have the exhaust discharge into one 3 inch and 2).2 inch to begin with and have no return? Size of shop 78 feet by 38 feet. A. The plan of dividing the exhaust with a 3 inch pipe and returning with a 2).2 pipe on each side is correct. The last ends of the return pipe should be open, so as to allow drip and excess of steam to escape freely. This arrangement prevents undue back pressure in the engine. All pipes should bc laid to allow water of condensation to run with the steam to drips or to the. end of the line. (6541) J. H. asks for a rule to find strain brought on staybolts. Also how to find horse power of an engine with the indicator. How to find displacement of steamship. A. The strain on a staybolt is the whole area of plate due to any one bolt multiplied by the steam pressure. If the stays are 6 inches apart in each direction, the area is 36 inches. You will need a book on the indicator for the horse power problem. See Pray's book, Twenty Years with the Indicator,' ' 2.50 by mail. The displacement is also an intricate problem. See Bagwell's Engineer's Pocketbook, 4 by mail. (6542) W. H. P. says: Inclosed is a twig from a Pirus Japonica bush growing in Philadelphia, which seems to be suffering from a white scale covering most of the stems, some of which are already dead and others dying. What is the remedy for this, if any ? A. Answer by the Entomologist, United States Department of Agriculture.--This is' the common scurfy bark louse (Chionaspis furfurue) found abundantly on pear, apple, etc. Spray about June 1 with dilute kerosene emulsion (1 part to 10 of water) or during winter with 1).2 pounds whale oil soap to 1 gallon of water.
