We give herewith engravings of two useful blowpipes, copied from the Rngitsfl Mechanic. The first illustration, Fig, To Correspondents. We have on hand a mass of interesting and valuable correspondence, and there must necessarily be some delay in its appearance; but it shall be attended to as fast as space will permit, and we shall be glad to get more of the same sort. If you have got anything practical you wish to bring forward send it along, and don,t be too diffident about sending it in homely dress. We will take care that it does not put to blush the orthography and grammar of those unskillful m writing for publication. WE invite the attention of our readers to the announcement for the forthcoming Volume, 1870, on another page It will be seen that premiums are to be given to all who send lists of snbsoribers of twenty names and upward. 1, consists of a wood stand, A, a fan with sheet-iron frame and wood sides, B, a small driving wheel, C, and a blowpipe D, with foot and blast tube running through its center connected by a flexible tube to the fan. E is the tube which conveys the gas to the flame, the gas escaping from an annuhr opening around the nozzle of the blast tube. F is a sheet- iron support for charcoal on which the article to be brazed is placed. Fig. 2 is a blowpipe for light work which a contributor to the paper alluded to above, says he has used, satisfactorily, for six years. F is the flame, G is a gas tube, M the mouth piece, H the hand of the operator to draw the slide, S S, out a little for a largo flame, and to compress it for a small one, T is the outside tube, into which tube, S 8, slides ; I is the iron wire stand ; W is a gas swivel, and P the gas pipe to swivel on the stand adjustable on I.