Collectors have bobs of ivory, bone, pottery and wood. Several catalogs had the same selection suggesting a common manufacturer.īut not all plumb bobs of this period were so mundane. Steel points were offered with some bobs and japanning was offered with some iron bobs. Most bobs offered in this general market were heart shaped, with an occasional turnip shape, and were made of brass, lead or iron. Symmetrical construction to assure the plumb bob would hang on its central axis, affixing the line on the central axis with the point, and the point itself were the improvements that brought us to the bobs we find in American hardware catalogs of the 1800s (Shannon, Walter's, Russell & Erwin, Hammacher Schlemmer etc.). The plumb bob evolved to meet requirements for accuracy in such functions as erecting tall buildings, installing machinery, mining and surveying. Illustrations of early plumb bobs appear in the December 1992 issue of The Plumb Line. An early improvement was the drilling of a hole to attach the line. Such crude bobs, with no thought yet of a point at the bottom, offered sufficient accuracy for their purpose. These very early bobs were simply shaped stones, sometimes with grooves around them to keep the line from slipping off. So I want to thank Bruce for sharing his knowledge and providing the photos for this article.Įgyptians certainly used plumb devices to build the pyramids, and perhaps others used them earlier. Bruce is General Manager of News Channel 15 in Fort Wayne and an avid plumb bob collector. This article takes its inspiration from several phone conversations with Bruce Cynar of Fort Wayne, Indiana and from his publication The Plumb Line.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |