62 KANSAS CITY REVIEW OF SCIENCE. 



SIGNALING BY ELECTRICITY. 



This electric-signaling apparatus consists of a relay having a movable arma- 

 ture and retractor and a device for alternately breaking and closing the circuit there- 

 of, combined with a local battery and circuit for operating registering apparatus, 

 the terminals Of which are controlled by the said relay-armature, whereby the 

 condition of the local circuit is changed both at the movement of the relay-arma- 

 ture from and at its movement toward the poles of its magnet. A record is thus 

 made both at the opening and closure of the main or relay circuit. 



MACHINERY FOR WAXING PAPER. 



This novel paper-waxing apparatus comprises a heated waxing-pan having a 

 bar beneath its surface under which the paper is required to pass. The paper is 

 then led to a pair of distributing, compressing, and calender rolls, located above 

 or nearly over said pan, and an independent smoothing and cleaning device is 

 located on the delivery side of said rollers. 



DESULPHURIZING FURNACE. 



A late and new process for desulphurizing ores consists of the following suc- 

 cessive steps: first, drying the ore; second, subjecting the dried ore in a close 

 chamber to thorough agitation ; third, subjecting the ore to the action of heat ; 

 and, fourth, injecting hot air which has been dehydrated or deprived of its moist- 

 ure. The air, before being admitted to the roasting-chamber, is dehydrated by 

 being forced through a body of common salt. 



ARTIFICIAL FILTRATION. 



As illustrations of the process of filtration on a large scale, nothing better can 

 be had, perhaps, than the filter-beds of the London Water Companies. They 

 cover altogether close upon eighty-four acres of ground; and though they vary 

 very greatly in their composition, the principle on which they are constructed is 

 the same in all cases, and any one of them may be taken to exemplify the opera- 

 tion. In practice, all the companies requiring to filter their water do so by al- 

 lowing it to stand in huge reservoirs, the bottoms of which are porous, and sup- 

 ported on brick *krches, which at once form the base of the filter-beds, and the 

 roof of a water-tank, from which the purified water is pumped up into the mains. 

 The composition of the filter-beds varies with each company. The New River 

 Company, the largest of them all, make their filters of two feet three inches of 

 sand, underneath which are three feet of gravel, increasing in coarseness toward 

 the bottom. Others are more elaborate. The Grand Junction Waterworks Com- 

 pany, for instance, make their filters by first depositing one foot of boulders, 

 over which are nine inches of coarse gravel, then nine inches of fine gravel, six 

 inches of hoggin, and two feet six inches of Harwich sand. The Lambeth and 

 the Chelsea Companies, again, construct their beds of shells, as well as sand and 

 gravel, though in different proportions, one having altogether eight feet of filter- 



