THE RIGHT BOOK COUNTS THE TECHNICAL GRADUATE starting out in his chosen profession should not fail to start a library of books on subjects of interest to him in connection with his work. BEGIN YOUR LIBRARY WITH PRACTICAL BOOKS You cannot do without these books Earth Dams-BURR BASSELL, 68 pages, 31 illustrations $1.00 Field Practice of Railway Location-WILLIAM BEAHN, 260 pages, 43 illustrations $3.00 Reinforced Concrete-A. W. BUEL AND C. S. HILL, 434 pages, 311 illustrations $5.00 Plat and Profile Book for C. E.-H. F. DUNHAM, 9x4 inches $1.00 Engineering Studies (Stone Arches)-FOWLER, illustrations, 6 parts each, $0.25 Railway Right-of-Way Surveying A. I. FRYE, 50 pages Index to Engineering News-1890 to 1899 inc. 25,000 references, paper. $0.50 Index to Engineering News- 1900 to 1904 inc., 25,000 references, cloth $2.50 Economics of Road Construction-H. P. GILLETTE, 40 pages, illustrated $1.00 Earthwork and Its Cost-H. P. GILLETTE, 256 pages, illustrated $2.00 $1.00 CONSULTING DEPARTMENT (Continued) Cutting Spirals on Milling Machines Question: Please tell me how to set a milling machine for cutting a spiral. For instance, if I have a 40 lead, how would I set the gears on my milling machine to cut that spiral both left and right?—I'. W'. Answer: Usually spirals cut on milling machines are designated in terms of inches to one turn. For instance, a spiral is said to be of 8 inches' lead, not that its pitch is turn per inch. The machines are so designed that in most cases, if change gears of equal diameter are used, the work will make a complete turn while it is moved lengthwise 10 inches; that is, the spiral will have a lead of 10 inches. To cut spirals you should always use the following formula: As shown in the formula, we have 80and 60-tooth gears for drivers and 40and 30-for driven gears. Then by putting the 80-tooth gear on the work, the 40-tooth gear first on the stud, the 60tooth gear second on the stud, and the 30-tooth gear on the screw, we could do the job. The correct position for the spiral bed may be ascertained in two ways-that is, graphically and by simple calculation and reference to tables. In determining it graphically, a right-angle triangle is drawn to scale, one of the sides which form the right angle representing the lead of the spiral. The other side represents the circumference of the piece, in inches; and the hypothenuse repre Mention The Technical World. 133 HIS Vest Pocket Light is not a toy. It TH gives instant light. smoke nor odor. trouble or danger. No chemicals, oil, No heat, matches, No wires to go wrong. Cannot be blown out by the wind. Invaluable in gas works, paint factories, mines, oil wells, paper mills, woodworking factories, etc. Useful for Miners, Hunters, Plumbers, Railroad Employees, Undertakers, Sailors, Soldiers, Travellers, Watchmen, Liquor Dealers, Physicians, Policemen, Machinists, and, in fact, for all purposes where a light is instantly required. Endorsed and used by the Army and Navy Departments of this and foreign countries. Adopted by nearly all of the Police and Detective Agencies of the world." Style A-Special $1.00 Style A-Metal Case Covered with Leatherette 1.25 1.50 Style B Extra Batteries, 30 cts., Extra Bulbs, 35 cts. THE W. G. NAGEL ELECTRIC CO., TOLEDO, OHIO Mention The Technical World. CONSULTING DEPARTMENT-(Concluded) sents the line of the spiral. The angle between the lines representing the line of the spiral and the lead of the spiral, is the angle of the spiral. This can be transferred from the drawing to the work by a bevel protractor. The second method of obtaining the angle of the spiral is to divide the circumference of the piece by the lead, and note the number of degrees opposite the figures that correspond with the quotient in any table of natural tangents. Thus, supposing the diameter to be 3 inches; then the circumference is 3×3.1416 (9.4248) inches. This quantity, divided by the lead, 10 inches, gives .94248, which corresponds to an angle of 43° 25′ approximately. All that is stated above refers to the cutting of right-hand spirals. If you are cutting left-hand spirals, the only changes necessary are the swinging of the spiral bed to the opposite side of the center line, and the introduction of an intermediate gear upon the stud to engage with either pair of change gears for changing the direction of rotation of spiral-head spindle. ALTERNATING-CURRENT PROBLEMS (Concluded from page 114) "vector") sum of these parts is equal to E. Example. Two coils b and c, Fig. 5, are connected in series between mains supplied from au alternator, of which the effective electromotive force is E. Then the total effective electromotive force E is subdivided into two parts E, and E2, which act upon the respective coils, as indicated in Fig. 5; and the "geometric" (or "vector") sum of E, and E, is equal to E, as shown in Fig. 6. The angles, and depend upon the relative resistance and reactance of the respective coils. It is to be noticed particularly that the arithmetical sum of E, and E, is in general greater than E. 2 2 EF it wuz hot enough ter roast beefsteak on de roof, en de beef wuz free ter us, we'd holler fer winter ter come 'long en freeze de ice cream. Mention The Technical World. The Felix G. L. Daus Duplicator Co. Daus Building, 111 John Street, New York City PATENTS Valuable and Saiable Patents Promptly Secured. SHEPHERD & PARKER, "During the past ten years Mr. Shepherd, of Shepherd & Parker, has obtained for us a great many important patents. We have no hesitation in heartily recommending him to anyone having need of the services of a patent attorney." HALLWOOD CASH REGISTER CO. BRAZE CAST IRON Opens up a new field of profitable work for 20 W.Randolph St. THE A. & J. MFG. CO. CHICAGO, ILL. Mr. Parker on November 1, 1903, resigned his position as an Examiner in the U. S. Patent Office to enter this firm. Address, 844 G. St., Washington, D. C. EYE BENDERS BUTCHER'S BOSTON POLISH Is the best finish made for FLOORS, Not brittle; will neither scratch nor deface, like shellac or varnish. It is not soft and sticky, like beeswax. Perfectly transparent, preserving the natural color and beauty of the wood. Without doubt the most economical and satisfactory POLISH known for HARDWOOD FLOORS. For sale by Dealers in Paints, Hardware and House Furnishings. Send for our Free Booklet, telling of the many Advantages of BUTCHER'S BOSTON POLISH. THE BUTCHER POLISH COMPANY 356 Atlantic Avenue, :: :: BOSTON, MASS. OUR No. 3 REVIVER is a superior finish for kitchen and piazza floors :: Mention The Technical World. Model of a Motor Car. By Hugo Güldner. Translated by Theodore Schulz. Pasteboard, 131⁄2 by 9 inches. Published by Thomas Whittaker, New York City. Price $1.75. THIS work consists of a brief description of the motor car, beginning with some historical references, and later taking up the construction of the various component parts of the automobile. The novel feature of the book consists of a paper model showing the assembly of the principal parts of the automobile. This model is arranged so that the representations of each of the principal parts fold together in such a way that, when assembled, a picture of a complete machine is shown; and these parts may then be unfolded so that each detail of the machine can be examined separately. The model is accompanied with a list of principal parts of the automobile, each of which is numbered so as to be identified on the model. American Steam Gauge & Valve Manufacturing Company, Boston, Mass. Folder on The American Special Pop Safety Valve. Paper, 81⁄2 by 11 inches. THIS circular describes the American Special Pop Safety Valve, which, it is claimed, affords absolute protection against boiler explosions from excessive pressure. This safety valve is designed for working pressures up to 300 lbs., and is tested for a pressure of 450 lbs. It is made in several different styles, the special features of which are explained at length in the circular. Mention The Technical World. |