76 ANNUAL OF SCIENTIFIC DISCOVERY. 



the lower part of this chamber, or bridge, being perforated with numerous 

 holes, opening from the interior of the bridge to the space beyond it, estab- 

 lished a direct communication between the outer air and the throat of the flue. 

 There was a second solid bridge beyond the first, descending from the upper 

 side of the flue ; this, by intercepting the direct channel through that part of 

 the passage, retarded the flow of the smoke and gases, and caused their per- 

 fect mixture with each other within the space between the bridges. The 

 result of this arrangement was, that a current of highly heated air, which 

 passed through the tubes in the furnace, escaped at the bridge through the 

 perforations in the back wall, and mixing with the gases from the furnace, 

 which held the smoke in suspension, converted the smoke into flame. It was 

 calculated that by the adaptation of this apparatus to marine boilers the high 

 temperature of the boiler-rooms would be obviated, and that the steam vessels 

 would not be so evident from a distance as they now, were, by the volumes of 

 smoke they give out. 



PULVERIZING MACHINE. 



A machine for the pulverization of sugar, gum, and other substances which 

 can not be easily ground without clogging, has recently been invented by 

 Mr. Chase, of Boston. 



The machine consists in a novel and ingenious application of stampers af- 

 fixed to a revolving plate attached to the central shaft, and acting within a 

 circular chamber or mortar. "Within this mortar is a circular disk, which oc- 

 cupies the center space, and is furnished with projections or wings on its 

 edge, which divides that part of the mortar nearest its outer edge into a 

 number of rotative cells or chambers. In each of these cells one of the 

 stampers is placed. When the machine is set in motion the stampers and 

 disks are carried round together, and the former are alternately lifted and 

 dropped by means of the gearing and cams placed around the center shaft. 

 Each stamper thus makes eighty beats during a single revolution of the shaft. 

 The cells are fed by the hopper through the spout inserted into the side of the 

 mortar, and, having made one revolution, are emptied through to another 

 hole at the bottom of the mortar into the bolting-sieve placed in the chamber 

 beneath the hopper. 



There is one peculiarity in the action of the stampers in this machine 

 which deserves notice : The sides of the cells in which the pounding takes 

 place, being constantly in motion, the material to be pounded is carried round 

 by them, and pushed along or turned over upon the fixed plate which forms 

 the bed of the mortar. By this action a fresh surface is constantly presented 

 to the blow of the stamper, and the ingredients to be pounded never can get 

 beaten into a hard, compact mass, as is often the case with fixed stampers, 

 and thus a very large amount of their power is rendered ineffective. 



ARRESTING AND REACTING SPRINGS FOR FIRE-ENGINES. 



The following extract from the specification of a patent granted Franklin 

 G-. Smith, of Columbus, Tennessee, sufficiently explains the nature -of the 

 above-entitled invention : 



