Riding the wave

Precision Weighing Scale

A very odd instrument at the Hydrographic Institute of the Navy is a special scale, probably used to measure the weight of windroses, therefore complementary to the compass.

It is very bulky and heavy, about 85x83x55 cm. The catalog quoted in "Bibliography" gives a description that is reproduced in full.

Steel yoke aluminum painted diamond shaped. Knives and flats in stainless steel, non integral, top central screw for adjusting the center of gravity, iron index pointing down. At the ends of the yoke the painted iron brackets have at the bottom an eyelet for suspending the pans and at top a bar can be laid down on the rocker arm to place scale at rest. The scale is characterized by an elaborate system of pans. To the brackets is suspended, by a hook and brass rods, an iron plate aluminum painted, diamond-shaped, with a central opening, which fits a first slightly concave brass dish. This in turn has a hook to which is suspended, by rigid rods, a second brass plate, which is also fitted with a hook. At the ends of the diamond plate two rigid rods are screwed that hold a third large diameter brass dish, slightly concave. Scale's support is also very complex. A painted iron tripod with leveling brass screws supports, with four brass screws, a wooden box of octagonal irregular shape, whose cover is made of a thick iron plate. Central to the latter is set a perforated column of cast iron, painted black, of triangular shape, that supports the yoke. The graduated scale, made of bone, is at the base of the column. Two elements also in cast iron carry the rocker arm that fastens the brackets. On the front of the scale is fixed, with a long pin and a wheel, the mechanism for lifting the pans. This one is fitted with a long brass tube that protrudes beyond the front foot support and that would suggest the existence of a window, currently missing.

Precision Scale
The Museum of the scales , in Campogalliano, has an identical specimen, #107 in the Catalog of the Museum, marked "Deleuil à Paris" (XIX century). That statement is missing on the specime at the Hydrographic Institute, where the plate with manufacturer's name is presumably lost.
By Paola Presciuttini