Framing of timber, Construction of roofs, Parker's and Hamelein's cements, Plaster in imitation of marble, To make glass and stone paper, Causes of the decay of timber, FORMULE FOR RUNNING LINES, LOCATING SIDE TRACKS, &c., TABLE OF CHORDS CORRESPONDING TO EVERY 100 FEET ON CURVE FROM 200 TO 1000 FEET, CALCULATED TO EVERY 15 MINUTES' THE MECHANIC'S, MACHINIST'S, AND ENGINEER'S PRACTICAL BOOK OF REFERENCE: CONTAINING TABLES AND FORMULÆ FOR USE IN SUPERFICIAL AND SOLID MENSURATION; STRENGTH AND ADAPTED TO AND FOR THE USE OF ALL CLASSES OF PRACTICAL MECHANICS. EDİTED BY CHARLES W. HACKLEY, Professor of Mathematics in Columbia College, N. P. THE PRACTICAL BOOK OF REFERENCE. ARITHMETICAL SIGNS. THE following definitions of arithmetical signs which are employed in mechanical calculations, will be found of great value to those who do not yet understand them, and of some interest to those who are already familiar with their meanings. This is the sign of equality, and signifies equal to. For example: 12 inches 1 foot (12 inches is equal to 1 foot). + This is the sign of addition, and signifies plus, or more. example: 5 + 3 8 (5 added to 3 is equal to 8). This is the sign of subtraction, and signifies minus, or less. example: 10 82 (10 minus 8 leaves or is equal to 2). For For × This is the sign of multiplication, and signifies multiplied by, or into. For example: 10 × 3 = 30 (10 multiplied by 3 is equal to 30). This is the sign of division, and signifies divided by. For example: 156 ÷ 6 = 26 (156 divided by 6 is equal to 26); or, 24 ÷ 4 = 6 24 4 (24 divided by 4 is equal to 6); or = 6 (24 fourths are equal to 6 wholes). :::: This is the sign of proportion, and signifies proportion. For example: 4: 6 :: 8: 12 (as 4 is to 6, so is 8 to 12); or 3: 5 :: 3 9 9:15 (that is, as 3 is to 5, so is 9 to 15); 5 This is the sign of the Square root. When it is placed before a number (as thus, √ 5 = 25), it means that the square root of that number is required. For example: 255, because 5 × 5= 25 or, √ 9 = 3, because 3 × 3 = 9; or, v 64 8, because 8 × 8 = 64. When it is placed before a that number is required. 16, and 4 × 16 = 64); × 36 = 216). This is the sign of the CUBE root. number, it means that the cube root of For example: 644 (that is, 4 × 4 or, 3/ 216 = 6 (that is, 6 × 6 = 36, and 6 |