PLUMB AND LEVEL INDICATOR.
Notwithstanding the insertion in a former number of an engraving similar to the one here presented, we, by special request, and by the consideration that the utility of the article has been tested, and some of them are now on sale, are induced to present again the subject to the attention of our readers. The utility of the Indicator far exceeds the expectations of the inventor, being found exceedingly convenient not only for masons, carpenters, ship-builders, but for topographical engineers, surveyors of land, road builders and farmers. It will be understood that the proper position of the instrument is vertical, and that the weight of the ball will keep the index in a perpendicular position; so that either the bottom or the side of the frame being placed against a horizontal, vertical, or oblique surface, the index will readily indicate whatever variation there may be, from a perpendicular or a horizontal line. They answer the ready purpose of a square, plumb or level, and by readily showing the level, or obliquity of braces, and the exact variation of vertical or horizontal surfaces, from horizontal or perpendicular lines ( which neither the spirit level nor the plumb-line will do) it may be considered among the indispendables. In describing specific angles, octagons, hexagons, &c. for timbers in carpenter and mill-work, they come to the point at once, and save three-fourths of the time ordinarily expended in laying out such work: and if a land holder has a mill stream, on which he would ascertain the quantity of fall in a given distance; or if a farmer would ascertain the distance and depth to which he must cut a drain; the elevation which he may obtain from an aqueduct; or the direction in which a standing tree is inclined, he will find the indicator ever ready to inform him. Besides the utility, it embraces a considerable share of elegance,—consisting of a neat mahogany frame 9 inches square, and glass, encasing a lithographic dial with an interesting picture (not represented in this cut) in the centre; and the movement of the index is so free, that a variation of one fourth of a degree is indicated. Measures are in progress for securing a patent. For sale at this office,—price one dollar single.