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42 known as Witness Dimensions, and the workman always follows these while manufacturing from scale drawings. The use of witness dimensions relieves the workman from responsibility for errors, transferring this responsibility to the draftsman or designer.

24. Related Mathematics on Garbage Can.—Problem 8A.—Compute the exact capacity of the garbage can, Fig. 61, in gallons.

Transposing a Formula.—Very often a customer requires a certain capacity in a vessel but does not care about the dimensions. In the example of Article 22 the diameter and the height