Transactions of the Society of Naval Architects and Marine Engineers Volume 3 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1895 edition. Excerpt: ...Fig. 4, lay off A B equal to the Length in Inches of Unity on the Tangent Scale. Set up B D peril pendicular to A B. Lay off B a such that-f-D = tangent of angle where secant is 1.01. Similarly, --is the tangent of B A the angle whose secant is 1.02, and so on. Then if a scale divided like B a b c d D is applied square to a section at a given point, with B on the next section on one side, the secant of the obliquity is indicated directly by the intersection of the next section on the other side with the scale. The auxiliary diagram of Plate 24 is simply a convenience for laying off the secant scales. The lines at top and bottom are graduated for various lengths of unity on tangent scale. Having determined the length of unity on tangent scale, as indicated in Table 5, a strip of paper is laid across at this length and the scale marked off. Plate 24 shows the method of laying off the secant scale for the Length of Unity on Tangent Scale = 13 inches. The dividing lines upon the body plan indicate the points upon the sections at which the obliquities are to be measured. It is to be noted that at the end and middle sections there is shown but one adjacent section. For the middle section we know the secant to be unity. For the end sections, where the secant is not unity, it is necessary to lay off on the secant scale twice the distance to the next section which appears upon the body plan. If, for instance, the distance to the next section corresponds to 1.015 upon the secant scale, it is not correct to take the secant as 1.030. Twice the distance corresponding to 1.015 must be measured off upon the secant scale, and the appropriate secant value taken off. Having filled in the table of secants, the half girths are measured from the half sections of the..