138 TABLES OF OFFSETS FOR RAILWAY CURVES, AND CORRECTION OF LEVELS FOR CURVATURE, ETC.
No. 2.-Offsets at Radius Cffsets in of curve inches and in chns.
the end of the first chain from tangent point of railway curves.
Radius Offsets in Radius Offsets in of curve inches and of curve inches and
Radius Offsets in of curve inches and in chns. decimals.
TABLE OF CORRECTIONS FOR CURVATURE, ETC.
No. 3.-Difference between apparent and true level for distances in chains. Correction in decimals of feet.
Distance For curva- || Distance For curva- ture and in ture and chains. refraction."
No. 4.-Difference between apparent and true level for distances in miles. Correction in feet and decimals. Distance For curva- Distance For curva-
RULE.-Multiply the area corresponding to the quarter girt in inches, by the length of the piece in feet, and the product will be the solidity.
NOTE. It may sometimes happen that the quarter girt exceeds the limits of the table; in this case, take half of it, and four times the content thus found will give the required content.
1. If a piece of round timber be 11 feet long, and the quarter girt 13 inches, what is the solidity?
Ans. By the table the area corresponding to the quarter girt 13 is 1.265; which, multiplied by 11 feet, the length, will give 13915, or 13 feet 11 inches nearly.
2. A piece of round timber 21 feet long, and the quarter girt 15 inches, how many feet are contained therein?
3. How many solid feet are there in a tree which is 35 feet. in length, its quarter girt being 101 inches ?
4. How many solid feet in a tree 32 feet long, its quarter girt being 8 inches. Ans. 14.208 feet.
5. How many solid feet in a tree 8 feet long, its quarter girt being 7 inches? Ans. 3.554 feet.
6. Required the content of a tree, whose length is 36 feet, and the quarter girt 26 inches? Ans. 171-536 feet.
7. What is the solid content of a piece of timber whose length is 15 feet, and quarter girt 13 inches?
8. Required the content of a tree whose length is 26 feet 9 inches, and quarter girt 144 inches?
Acute angle defined, 1. Acute angled triangle defined, 2. Addition, sign for, 18.
Angie defined, 1; acute, defined, 1; obtuse, defined, 1; right, defined, 1; measure of, term described, 3.
Angle, problems on the:-to divide an, into two parts, 7; to set off an, to con- tain a given number of degree, 7; to measure an, contained by two straight lines, 7.
Angles, measurement of, 8; of polygons, to find the, 10; vertically opposite are equal theorem, 16.
Arc of a circle defined, 3.
Arc of a circle, problems :-the chord and height being given, to find the diameter and chord of half the arc, 26; formulæ and examples, 26; to find the length of any, 28; formulæ and examples, 28. Arched roof, to find the concave surface
of an, 90; examples, 90; to find the solid content of, 90; examples, 90. Area, to find the, of irregular figures, 50; examples, 50. Artificers' work, methods of measuring,
80; bricklayers', 80; carpenters', 83; glaziers', 88; joiners', 83; masons', 82; painters, 88; paviours', 89; plasterers', 87; plumbers', 89; slaters', 86; tilers',
(6.) To find a third proportional to two numbers, 75. (7.) To find a fourth proportional to three numbers, 75. Carpenters' work, method of measuring, 83; doors, 84; joists, 83; partitions, 83; roofing, 84; staircases, 84; balustrade, 84; wainscoting, 84; window-shutters, 85; examples, 85.
Chain, Gunter's, described, 92; method of using, 94; land surveying by the, ex- plained, 108.
Chain and cross, land surveying with, de- scribed, 97.
Chimney, method of computing the brick- work of a, 80.
Chord, term defined, 3.
Circle, definition of, 3; arc of described, 3; diameter of, defined 3; divisions of, described, 3; radius, term defined, 3. Circle, problems on the:-to find the cen- tre of a, 8; to describe the circumfer- ence of a, through three given points, 8; to draw a tangent to a, through a given point, 8; to find the diameter and cir- cumference of a, the one from the other formula and examples, 25; in a given, to inscribe any regular poly- gon, or to divide the circumference into any number of parts, 10; in or about a, to describe a square or an octagon, 12; in a, to describe a trigon hexagon, or a dodecagon, 12; in a, to inscribe a pen- tagon or decadon, 13; example, 13; to inscribe a, in a given triangle, 11; to describe a, in or about a given square, 11; example, 12; to circumscribe a, about a given triangle, 11; example, 11; about a, to circumscribe any regular polygon, 10; to find the area when the radius or half diameter is given, 42; ex- amples, 42; when the circumference is given, 42.
Circle, arc of a, the chord and height being given, to find the diameter and chord of half the arc, 26.
Circle, arc of a, to find the length of any,
28; formulæ and examples, 28. Circle, segment of a, to find the area of, 45; formulæ and examples, 45. Circle, sector of a, to find the area of, 43; formulæ and examples, 43.
Circles, concentric, to find the area in- cluded between two, 47; formulæ and examples, 47; tables of areas of seg- ments, 137.
Compasses described, 95.
Cone defined, 53; to find the solidity of any, 58; to find the convex surface of a right, 58; formulæ and examples, 58. Cone, frustrum of a, to find the solid con- tent of a, 60; formulæ and examples, 60; to find the convex surface, 61; rules and examples, 61. Cross described, 93.
Cube, definition of, 53; problem relating to the, 55; to find the solidity, of, 55; formulæ and examples, 55. Cube root, symbol of, described, 18. Curvature, correction for, described, 118; table of corrections for, 138. Curves, railway, method of laying out de- scribed, 127; forms of, explained, 127; to lay out a curve by the common method, 127; examples, 128; to lay out a curve by offsets from its tangents, 129; examples, 130:-(1.) When the length does not exceed one quarter of its radius, 129. (2.) When it is any required length, 130; table of offsets for, 138.
Cuttings, railway, to find the contents of, 130; tables described, 130; to take the diameter, 131; to find the contents from the depth, 132; examples, 182; to find the content from the sectional areas, 133; examples, 134. Cylinder described, 53; to find the so- lidity of any, 57; formulæ and exam- ples, 57; to find the area of the surface, 57.
Datum, line, use of, explained, 122.
Decagon, to inscribe a, in a given circle,
Degree, term described, 3.
Diameter of a circle defined, 3. Division, sign for, described, 18. Dodecagon, to describe a, in a given circle, 12.
Dodecakedron, described, 54.
Dome, to find the surface and solidity of a, height and base given, 91; examples, 91.
Ellipse, to draw an, 15; with thread, de- scribed, 15.
Ellipse, problems relating to the :-to con- struct a figure resembling an, by circu- lar arcs from four centres, 14; to de- scribe a true, 15; given any three of the four following parts to find the fourth traverse axis, conjugate axis, the abscissa, and the ordinate, 31; to find the area of an, 48; formulæ and examples, 48; given the axis to find the circumference, 32; formulæ and examples, 32; segment of an, to find the area the chord of which is parallel to one of the axis, 48; examples, 48. Engineering, surveying, 115; levelling, term defined, 115, practice of, described,
120; instruments described, 115; Y- level, 115; levelling staves, 11s; cor- rection of curvature, 118; for refrac tion, 119; contents of railway cuttings, 130; method of laying out railway curves, 127.
Equality, sign for, 18.
Equilateral triangle defined, 2.
Estates, method of surveying large, by the chain, described, 113. Exercises, promiscuous, 52.
Field book described, 96; method of en- tering notes, 96; example of, 180. Fields, four-sided, method of surveying with chain and cross, 100; to find the content, 100; examples, 100.
Fields contained by more than four sides, method of surveying with chain and cross, described, 101; to find the con- tent, 101; examples, 101.
Fields, included by curved sides, method of surveying with chain and cross, de- scribed, 104; examples, 105.
Fields in the form of trapeziums, method of surveying with chain and cross, 99; examples, 99.
Fields, triangular, to measure with chain
and cross, described, 93; construction, 98; to find the content, 98; examples, 98.
Fields, four-sided, method of surveying with chain alone, 111; examples, 111. Fields with more than four sides, 111; examples, 112.
Fields, triangular, to survey with chain, 108; examples, 108.
Figures all similar are like to one another, as the squares of their homologous or like sides: theorem, 17.
Frustrum, term defined, 54; parabolic, to find the area of a, 49; formulæ and ex- amples, 49.
Geometrical theorems, 10.
Geometry, practical problems, 4. Glaziers' work, method of measuring, 88; examples, 88.
Globe, to find the content of a, 55; for- mulæ and examples, 65.
Gravatt's levelling staves described, 118. Gunter's chain described, 92; method of using, 94.
Height of a pyramid, term defined, 54; of a solid, term defined, 54. Heptagon described, 3. Hexagon defined, 3; to form a, on a given line, 9; to describe a, in a given circle, 12.
Hexahedron described, 54. Hyperbola, to construct a, 16,
Icosahedron described, 54. Irregular pyramid defined, 54. Isosceles triangle defined, 2.
Joiners' work, measurement of, see Car- .penters'.
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