50 ANNUAL OF SCIENTIFIC DISCOVERY. 



piston head. The packing is metallic; within the head are four arms, 

 connected by joints at one end with the packing, and at the other with 

 the central rod before named ; by raising or lowering the rod, the packing 

 will be loosened or tightened ; the engineer, therefore, when he desires to 

 move the packing, merely turns a nut at the top of the piston rod. 



Improved Slide Valve for Steam Emjines. In this invention, by E. D. 

 Leavitt, Jr.. of Lowell, Mass., the back of the valve is fitted to the cover of 

 the steam chest, between which and its seat it works steam-tight. The 

 improvement consists in a certain method of compensating for the wear of the 

 valve and the two faces between which it works. There is an arrangement 

 whereby the valve is more perfectly balanced than by the ordinary method. 

 The valve is made tapering in a transverse direction, but in a longitudinal 

 direction its two faces are parallel By thus tapering the valve, one of its 

 sides is caused to have a greater area than the other, and the steam, by 

 exerting a greater pressure on the larger area, tends to force the valve between 

 the faces in which it moves, and thus keeps it always tight. 



RECENT IMPROVEMENTS IN STEAM BOILEES. 



Neiv Condenser for Marine Steam Boilers and Furnaces. James Biden, of 

 Gosport, England, has obtaineda^pateat-fhr feeding fresh water to marine 

 steam boilers, which water be^fibt^i^ by'th_e condensation of the steam after 

 it has been employed iny^^cylindjTs^of > the e'ngingk This he carries into 

 effect as follows : He lGraa pipe from the cylinde^ mto the water outside 

 of the ship at one side, |aQ3 after ^anyiog it round the srem of the vessel, he 

 causes it to enter the vassel atVMre'athersid4^ftH"* open iJto a reservoir in the 

 hold of the ship. A pipfc opes from the reservoir t&tha^itrnosphere, to allow 

 any uncondensed steam tXjtaf^Cfcfij Xs tne.s^e^i rami the cylinders passes 

 through the water of the oceaTi^(rlffl(^Mhe%n^4fDeconies condensed, and 

 the fresh . water thus produced fiowsnnto" tne reservoir, from which it is 

 pumped into the boilers. This invention is really an outside condenser the 

 ocean being made the grand cooler. The condenser pipe must be set on 

 an incline, to allow the condensed water to flow into the reservoir. 



Duppd's Furnace. An improvement by Thomas Duppa, of France, con- 

 sists in arranging and combining -several upright cylinder boilers in a circle. 

 Each boiler has its furnace at the lower end. At the upper part of each fire- 

 box a series of tubular flues rise to the upper part, where they communicate 

 with a chamber which is surrounded with the steam in the upper part of the 

 boiler. The heated air and products of combustion then pass down from 

 each boiler to the outside of a cylindrical vessel, into which the steam from 

 the series of boilers is conducted, then they pass off to the chimnc} r . The 

 object of this arrangement of boilers is to superheat the steam, and economize 

 horizontal space, by employing a number of vertical boilers instead of 

 horizontal ones. 



Safety Boiler Apparatus. The following is a description of an arrange- 

 ment recently brought out in England for preventing explosions in steam 

 boilers. The apparatus consists of an elbo\v-pi;>e. connecting the furnace 



