This book describes the intricacies of construction and fabrication more than 150 years ago of masts and yards installed in American merchant vessels, particularly those spars which were "built" or composed of multiple pieces bound together by iron bands. These were referred to as ""made"" spars as opposed to spars which were constructed from a single tree. It also contains instructions for developing the shape and proportions of various spars. Very little information is available on this subject. Generally, the external sizes of individual spars can be found but intimate details are sorely neglected. In addition the book includes the spacing and location of masts in a ship, and the rake. It also includes a discussion of the types of wood that are most desirable in the construction of spars.
Before his retirement in 1972, William L. Crothers worked as a draftsman in the design division of the Philadelphia Navy Yard. He is also the author of a book on the construction of American clipper ships.