By GUSTAVE SONNENBURG.

To avoid the long and time-consuming laying out of a boat by ordinates and abscissas, I have constructed a handy apparatus, by which it is possible without much trouble to obtain the sections of a vessel graphically and sufficiently accurate. The description of its construction is given with reference to the accompanying cut. A is a wooden rod of rectangular section, to which are adapted two brackets, a a, lined with India rubber or leather; a is fixed to the wood, a is of metal, and, like the movable block of a slide gauge, moves along A. In the same plane is a second rod, perpendicular to A, and attached thereto, which is perforated by a number of holes. A revolving pin, C, is adapted to pass through these holes, to which a socket, D, is pivoted, C acting as its axis. To prevent this pin from falling out, it is secured by a nut behind the rod. Through the socket, D, runs a rod, E, which carries the guide point, s, and pencil, s. Over s a rubber band is stretched, to prevent injury to the varnish of the boat.

Back of and to A and B a drawing board is attached, over which a sheet of paper is stretched.

THE FRAME TRACER.

THE FRAME TRACER.

The method of obtaining a section line is as follows: The rod, A, is placed across the gunwale and perpendicular to the axis of the boat, and its anterior vertical face is adjusted to each frame of the boat which it is desired to reproduce. By means of the brackets, a and a, A is fixed in place. The bolt, C, is now placed in the perforations already alluded to, which are recognized as most available for producing the constructional diagram. At the same time the position of the pencil point, s, must be chosen for obtaining the best results.

Next the operator moves along the side of the boat the sharpened end, s, of the rod, E, and thus for the curve from keel to gunwale, s describes a construction line. It is at once evident that a, for example, corresponds to the point, a. The apparatus is now removed and placed on the working floor. If, reversing things, the point, s, is carried around the construction curve, the point, s, will inscribe the desired section in its natural dimensions. This operation is best conducted after one has chosen and described all the construction curves of the boat. Next, the different section lines are determined, one by one, by the reversed method above described. The result is a half section of the boat; the other symmetrical half is easily obtained.

If the whole process is repeated for the other side of the boat, tracing paper being used instead of drawing paper, the boat may be tested for symmetry of building, a good control for the value of the ship. For measuring boats, as for clubs and regattas, for seamen, and often for the so-called Spranzen (copying) of English models, my apparatus, I doubt not, will be very useful. - Neuste Erfindungen und Erfahrungen.