EXAMPLES.

1. How many feet of glass are contained in a window which measures 7 feet 10 inches by 4 feet 7 inches ? By Cross Multiplication. Ft. In. Pa.

2. A pane of plate glass measures 2 feet 8 inches by 1 foot 6 inches; what did 8 such panes cost, at 14s. 6d. per square foot? Ans. £.23 4s. 3. The diameter of a circular window is 2 feet 91 inches; for how many feet must the glazier be paid, taking the window as a square?

Ans. 7 ft. 9 in. 61 pa. 4. The base of a triangular sky-light measures 10 feet 6 inches, and the perpendicular 5 feet 8 inches; what did it cost glazing, at 1s. 10d. per square foot? Ans. £.2 14s. 6d.

5. There is a house with three tiers of windows, four in a tier; the height of the first tier is 7 feet 2 inches, of the second 6 feet 4 inches, and of the third 5 feet 8 inches; and the breadth of each window is 4 feet 6 inches. The height of a semi-circular window, above the door, is 2 feet; what did the whole cost glazing, at 2s. 6d. per square foot?

PLUMBERS' WORK,

Ans. £.44 2s. 6d.

PLUMBERS' work is generally done at so much per pound, or else by the hundred weight of 112 pounds; and the price is regulated according to the value of the lead at the time when the work is performed.

Note. Sheet lead, used in roofing, guttering, &c. commonly weighs from 7 to 12 pounds per square foot; and leaden pipe varies in weight, per yard, according to the diameter of its bore in nclies.

The first of the following Tables shews the weight of a square foot of sheet lead, in pounds, to each of the subjoined thicknesses, in tenths and hundredths of an inch; and the second exhibits the general weight of a yard of leaden. pipe, according to the diameter of its bore.

Sheet Lead. Square Foot. Sheet Lead. Square Foot.

EXAMPLES.

1. A sheet of lead measures 18 feet 10, inches in length, and 5 feet 6 inches in breadth; required its weight, at 94lb. to a square foot.

As 1 ft. 9 lb. 8 oz.:: 103 ft. 7 in.; 8 cwt. 3 qu. 4 lb. . 0 oz. 10 dr. the weight required.

2. What is the weight of a sheet of lead, whose length is 15 feet 10 inches, breadth 4 feet 6 inches, and thickness or .2 of an inch? Ans. 840.53625 pounds. 3. If I buy 150 yards of leaden pipe, whose bore is 1 inch; what will it cost me, at 3d. per pound, admitting each yard to weigh 21 pounds?

Ans. £49. 4s. 44d.

4. What cost the covering and guttering of the roof of a church with lead, at £.1 18s. per cwt.; the length of the roof being 82 feet 9 inches, and its girt 65 feet 3 inches; the length of the guttering 165 feet 6 inches, and its breadth I foot 9 inches; admitting the thickness of the lead to be of an inch?

Ans. £.948 15s. 111⁄2d.

PAVERS' WORK.

PAVERS estimate their work by the square yard; and such dimensions must always be taken as will give the

true area.

EXAMPLES.

1. A rectangle measures 85 feet 9 inches in length, and 43 feet 6 inches in breadth; how many square yards of paving does it contain ?

2. The base of a triangle measures 76 feet 8 inches, and the perpendicular 42 feet 3 inches; what did it cost paving with Aberdeen granite, at 10s. 6d. per square yard? Ans. £.94 9s. 6d.

3. If the parallel sides of a trapezoid be 68 feet 7 inches, and 45 feet 3 inches, and their perpendicular distance 98 feet 6 inches; what will it cost paving with Guernsey pebbles, at 6s. 6d. per square yard? Ans. £.202 8s. 113d. 4. How many yards of paving does the trapezium contain, whose diagonal measures 136 feet 8 inches,

and perpendiculars 68 feet 2 inches, and 56 feet 4 inches? Ans. 945 yds. 21 ft. 5. The length of a street is 538 feet 6 inches, and its breadth 65 feet 8 inches; what did it cost paving with Purbeck-stone, at 5s. 6d. per square yard? Ans. £.1080 9s. 91d.

6. A rectangular court-yard measures 96 feet 9 inches in length, and 74 feet 6 inches in breadth. Across the middle and round the extremities of the yard, is a foot-way, 5 feet 3 inches broad; and paved with Guernsey granite, at 9s. 6d. per square yard. The rest is paved with Jersey pebbles, at 5s. 9d. per square yard; required the expense of the whole.

Ans. £.272 8s. 3 d.

VAULTED AND ARCHED ROOFS. ARCHED Roofs are either vaults, domes, saloons, or groins.

Vaulted roofs are formed by arches springing from the opposite walls, and meeting in a line at the top. Domes are made by arches springing from a circular or polygonal base, and meeting in a point at the top. Saloons are formed by arches connecting the side walls to a flat roof, or ceiling, in the middle.

Groins are formed by the intersection of vaults with each other.

Vaulted roofs are commonly of the three following

sorts.

1. Circular roofs, are those whose arch is some part of the circumference of a circle.

2. Elliptical or oval roofs, or those whose arch is an oval, or some part of the circumference of an ellipsis.

3. Gothic roofs, or those which are formed by two circular arcs, struck from different centres, and meeting in a point over the middle of the breadth or span of the arch.

Note. Domes and Saloons are of various figures; they, howeyer, seldom occur in the practice of measuring; but most cellars are covered either with vaults or groins.