MESSRS. EDITORSIn the Scientific American for Nov. 20, a table of lumber measure is given which will not answer in this section, because lumber IS too scarce. The following ' rule is that which is generally adopted in this part of Jersey and in Pennsylvania:Extract the square root of half the square of the diameter, which gives the side ot the greatest square contained in the circle; the other, and most simple rule, and that which lumbermen find most convenient, is to multiply the diameter by 5 and divide by 7, which will also give the side of the square,which, when once found, the number of feet of lumber measure can easily be found in one foot of the log's length; then multiply the whole length of the log by the one foot, and you have the number of feet in it. I could give you a large table of diameter of logs, but I do not wish to trespass on your columns by many figures. CHAS. E. MOORE. Groveville, Mercer Co., N. J.