Axis Of Shaft Of Wind-Mill With Horizon

8° upon level ground.

Breadth of whip at axis, 1/30 length of whip.

Depth u " 1/40

Breadth of whip at end, 1/60 "

Depth " " 1/80 '

Width of sail " 1/3

Divided by the whip in the proportion of 5 to 3, the narrowest portion being nearest to the wind.

Width of sail at axis, 1 length of whip; distance of sail from axis, 1/7 length of whip.

Cross-bars from 16 to 18 inches apart.

Strength Of Ice

Thickness, 2 ins. will bear infantry.

" 4 " cavalry or light guns.

" 6 " heavy field guns.

" 8 " upon sledges, a weight not exceeding 1000 lbs. per square foot.

Stiffness Of Beams

(Tredgold.) l2WC l2WC

3√-------= d;--------=b;b representing breadth, and d depth in inches, b d3

I length in feet, and W load in lbs. upon the middle.

C = Pine, .01; Ash, .01; Beech,.013; Elm,.015; Oak,.13; Teak,.008.

When the beam is uniformly loaded, put .625 W instead of \V.

Vernier Scale

The Vernier Scale is ll-10ths, divided into 10 equal parts; so that it divides a scale of 10ths into 100ths when the lines meet in the two scales.

How To Compute The Weight Of Cast Metal By The Weight Of The Pattern

When The Pattern Is Ok White Pine

Rule. Multiply the weight of the pattern in pouuds by the following multiplier, and the product will give the weight of the casting:

Iron, 14; Brass, 15; Lead, 22; Tin, 14; Zinc, 13.5.

How To Find The Weight Of A Cast Iron Beam Of Given Dimensions

Rule

Multiply the sectional area in inches by the length in feet, and by 3.2, the product equal the weight in pounds.

Example

Required the weight of a uniform rectangular beam of cast iron, 16 feet in length, 11 inches in breadth, and 1½ inch in thickness.

11 X 1.5 X 16 X3.2 = 844.8 pounds.

Hollow Columns

Hollow columns fail principally by crushing, provided the length does not exceed 25 diameters ; indeed, the length does not appear to affect the strength much till it exceeds 50 diameters.

The comparative strength of different forms and of different thicknesses will appear so distinctly from the experiments below, made by Mr. Hodgkinson, that no difficulty will be found in ascertaining the strength due to any size or form of column that may be required.

How To Find The Strength Of Any Hollow Wrought Iron Column

Sec. area. sq. ins. X

Tons per inch, corresponding to the proportions of length and thick- = ne.-;s to width as per tables

Breaking weight, tons.