132 ANNUAL OF SCIENTIFIC DISCOVERY. 



an alami-bell, operated by clock-work, which goes into action as 

 soon as the wire is slacked. By ciianging the tension of the cop- 

 per-spring, the instrument may be set to go oft" at any tempera- 

 ture, indicated l)y a dial and pointer attached to the regulating- 

 screw. Wlien exhibited to the meeting, the instrument was 

 started by holding it, for a moment, over a gas-flame, and by 

 the mere warmth of the breatli. 



Steam Generators. — A novelty was exhibited, at the exhibition 

 of the American Institute, by Thomas Mitchell, of Albany, ^. Y. 

 It is a cylinder of wrought iron with welded joints, into which 

 water is thrown by a feed-pump ; the same pump operating 

 through a worm gear to slowly rotate the cylinder in the furnace 

 where it is suspended upon two journals, one at either end of the 

 furnace. The design is to only throw water into the revolving 

 generator, as wanted, to make steam. The steam is generated 

 under very high pressure. The water is injected through a core- 

 pipe in one of the journals which extends longitudinally through 

 the axis of the cylinder, and is perforated at intervals throughout 

 its length. The water is thus subdivided into small jets, which 

 the heat of the cylinder converts into steam instantaneously. 



A big Belt. — The New York Belting and Packing Company 

 have lately had on exhibition at their store. New York, an India- 

 rubber belt 4 feet wide, 320 feet long, and weighing no less than 

 3,600 pounds. It is intended for the main driving-belt of the 

 larorest ":rain elevator in Ciiicao:o. 



The Joy Hammer. — This hammer is peculiarly adapted for 

 drawing down iron or steel, in which operation a rapid succes- 

 sion of uniform blows is required, with only a gradual alteration 

 in the force of the successive strokes. 



It therefore becomes possible to dispense with the complica- 

 tion of separate valves, and thus remove much of the risk of 

 derangement and source of wear. 



In this instrument the ram contains openings which are brought 

 by its own motion into communication with passages i'ov the inlet 

 and escape of steam, and thus cause its motion to be automati- 

 cally reversed. The only valve in the hammer is the throttle- 

 valve governed by a treddle, and by the adjustment of its open- 

 ing both the rapidity and force of the blows is at the same time 

 regulated. As many as 500 blows in a minute may be readily 

 struck, and from the sim})licity and solidity of all parts there is 

 the least possible chance of derangement. 



Safeli/ Nitro-Glycerine. — We learn from the "London Alining 

 Journal " that a series of interesting experiments for protecting 

 nitro-glycerine were recently' made at the ^lanorlicld House. A 

 small quantity of the material was put into a basin, and hot water 

 w:is poured upon it, the result being that in two minutes the orig- 

 inal oil sunk to the bottom, and (the >urplus water being poured 

 ofl") was run into a small phial ready ibr use. Into tliis the fuse 

 (pointed wiili a pcircussion cap) was inserted, and fired, and the 

 loud exi)l()>i(m testified to the unimpaired force <>f the nitro-gly- 

 cerine thus recovered. It is obvious th:it by this invention this 

 highly dangerous but very useful compound can be conveyed by 



