As the engineering public is gradually becoming educated to the realization of the economy of keeping boilers clean, a considerable number of devices have been patented to meet the demand for a good tool to clean out flues.

Brushes have been tried, but the deposit which forms in flues needs something more powerful than them for its effectual removal.

We last week illustrated an improved boiler flue scraper, and this week we lay before our readers a description and engraving of another device for the same purpose, the invention of Mr. E. L. Pratt, deceased, late of Beverly, Mass., a patent for which was granted to H. L. Pratt, administrator, May 11, 1869.

This scraper consists of two tapering heads, the broad parts of each facing the other, fixed upon a pipe or rod at a short distance from each other. The broad ends of the heads have mortise-like recesses formed in them, which receive the ends of the cutters; the mortises being large enough to admit considerable play of the cutters to and from the longitudinal axis of the instrument.

Each of the cutters has two cutting edges at right angles with its longitudinal axis; so arranged that any part of the surface, omitted by the forward one, shall be scraped by the other. These are also contracted in the middle into a shape approximating the section of an hour-glass, so that all the soot falls into the central part of the instrument between the cutters, and is drawn out with it.

The cutters are pressed out against the sides of the flues by elliptical plate springs, which also permit the scraper to enter and clean flues of various sizes. The cutters are to be made of chilled iron which will render them very durable.

From the cutting edges of the cutters extend, toward each head, ribs which facilitate the entrance of the instrument; and they also have a central rib extending between the cutting edges, which facilitates the entering of the hinder cutting edges, while it is sufficiently depressed not to interfere in the least with their operation.

The scraper is so cheaply made that it is designed to furnish them for every diameter of tube, and in such case, the cutting edges are made to fit the curvature of the interior surface of the flue. It is claimed that this scraper is cheaper, more durable, and effective than any form of wire brush.

Orders should be addressed to Miller's Falls Manufacturing Co., 87 Beekman St., New York city.

Scientific American, Vol. 20, June 5, 1869,
(New York, N. Y.: Munn & Co.)

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