With ceiling upon the first floor of 9 ft. and on the second floor of 8 ft.

He has another house, the gross cubical measurement of which is 12,410 cu. ft., upon which he is figuring. At the same rate per cubic foot, how much should his bid be to make $350 profit?

3. An office building has 10 floors, each 40 ft. by 72 ft., with 10 ft. ceilings throughout. The building cost $72,000. What is the rate per cubic foot?

4. What should be the cost of an office building of 9 floors, each 64 ft. by 36 ft. with 10 ft. ceilings, figured at the cubic rate upon the basis of the cost of the building described in No. 3?

5. On an estimate basis of 91 a cubic foot and 20% added basis, find the contract price for a house of 47,500 cu. ft.

Lesson No. 32. Review

EXERCISES

1. Find the area of a 4-sided figure having 2 sides parallel. The lengths of the parallel sides are 18 ft. and 10 ft. respectively, and the perpendicular distance between them

3. The cross-section of a canal is as shown in the diagram: 21 ft. wide, 12 ft. the greatest depth, 8 ft. deep to A or to B, with CD 15 ft. Find the cost of the excavation necessary per 100 lineal yards at 24¢ a load.

4. Find the value at $22 per thousand of the lumber necessary in building a tight board fence 13 ft. high around an athletic field 48 rd. square.

5. How many lots of acre each can be cut out of a piece of city property 360 rd. by 180 rd.?

Lesson No. 33. Painting, Paperhanging, Roofing, and Slating

In painting, the rule is to measure wherever the brush goes and to charge by the superficial yard, except where it becomes necessary to work to a line, as in the case of skirtings, to prevent the floor or wall from being soiled, technically termed "cut on both edges."

A great deal of work, such as cornices, window sills, balusters, brackets, etc., should be estimated separately.

Paperhanging is paid for by the number of pieces or rolls. Odd yards are charged as one piece. The pumicing and preparing of walls should be considered in making a bid upon a particular piece of work. Charge for hanging and borders at a fixed rate per dozen yards running.

Measure roof slating by the square of 100 superficial feet. In measuring allow 6 in. extra for connections where there will be cutting and waste.

Measure gravel roofing by the square of 100 ft. Consider in the estimate the number of plies of tarred felt and the quantity of pitch and gravel used to the square. Make no deductions for traps smaller than a yard square.

Gasfitters' and plumbers' work is usually estimated by the foot, running, according to the size and quality of pipe, with extras for elbows, crosses, sockets, etc.

EXERCISES

1. Find the cost of painting 294 doors (both sides) each 4 ft. 6 in. by 9 ft. 4 in., at 221 a square yard.

2. The flat roof of a city building is of the shape shown in the drawing and of the following measurements:

Find the cost of covering the roof with tarred felt and gravel at an expense of $9.36 per square of 100 ft., allowing for one opening, No. 2, which is 12 ft. on each side.

3. The roof of a dwelling house is of the shape shown in the drawing. The main building, ACDB, is 24 ft. by 32 ft.

The gables at AB, CD, and EF are of the dimensions shown in this drawing; that is, all three are the same size. The

right wing extends 15 ft. from the main building; that is, from BD. Allow 6 in. extra, 1 ft. in all, along each of the lines GL and GM for cutting and waste, and find the number of squares of slating necessary for the roof.

4. If wall paper is 18 in. wide and a single roll is 24 ft. long, how many rolls will be required for the 4 walls of a hall 48 ft. by 36 ft., and 18 ft. high?

5. With paper 18 in. wide, at 40¢ a roll, what will it cost to paper the 4 walls and ceiling of a room 24 ft. by 36 ft., and 12 ft. high? Consider the rolls 24 ft. long.

Lesson No. 34. Strength of Rods

By the tenacity of a body is meant its strength to resist tension (pulling) in the direction of its length. It is evident that the strength of a rod to resist tension depends upon the tenacity of its fibers, and hence must be proportional to the number of those fibers, or to the area of the cross-section.

For instance, the tension of the rod C is found to be proportional to the area of the cross-section; that is, if a rod with cross-section area B will hold 10,000 lb., a rod A twice as thick, measuring the diameter, will hold 40,000 lb., because the area of A is four times the area of B.

Very often it is necessary for others than practical engineers to be able to find out the tension of ordinary