I have taken the following from Ellis' Practical Treatise on Joiner' s Work, because it seems to me to be about the best thing written on the subject, at least, the best I have come across. ''The amount of going and rise given depends chiefly upon the amount of floor space allotted to them, and upon the height of the story; but subject to these restrictions, there is room for considerable variation. To obtain a stair that shall not be fatiguing or awkward to ascend or descend, the going should bear a certain ratio to the rise. Various methods have been proposed by writers on the subject to obtain the ratio, of which the following are the best known and most practiced:
"1. It is assumed that the average length of step in walking on the level is 24 in., and that it is twice as difficult or fatiguing to climb upward as it is to walk forward. From these premises it is deduced that one going one step forward, plus two rises or steps upward, should equal 24 in., which put in the form of a rule becomes,
"To Find the Rise When the Going Is Known.—Subtract the given going from 24 in., and divide the remainder by 2 for the rise.
"To Find the Going When the Rise Is Known.—Multiply the given rise by 2, and subtract the product from 24. The remainder is the proportionate going required.
"2. The product of the going and rise multiplied together is to equal 66.
Example: Going 11 in. x 6 in. = 66, and 7 in. rise x 9 3/7 in. = 66. Rule by this method: Divide 66 by the given rise or going to ascertain the proportionate going or rise.