82 ANNUAL OF SCIENTIFIC DISCOVERY. 



projection, and fitted together in parts. Rusting can be prevented by the 

 use of the new metal aluminum as a coating, and this process, if not too 

 costly, would be far more effective even than galvanizing. By the electro- 

 deposit process the spire might be gilt upon its entire surface. 



ELLITHORP'S IKON PAVEMENT. 



This form of pavement, said to be the best yet brought out, is made of a 

 series of groined arches, alternating in position in each adjoining row, to 

 make a surer foothold for horses travelling over it, and to prevent the wheel 

 of a vehicle from jamming in it. The blocks are kept in place by a flanged 

 projection catching over one block and under the next, so that when once 

 properly placed, there is no chance of then 1 being disturbed by the travel upon 

 them, while* they can be readily taken up and replaced when required. 



IMPROVEMENT IN THE MANUFACTURE OF GUNPOWDER. 



E. Hah 1 , of Dartford, England, has obtained a patent for an improved 

 method of sprinkling the gunpowder materials while under the mining pro- 

 cess. Under the old system of wetting with a watering pot, the distribution 

 of the water was not uniform, and the powder was not properly damped. Mr. 

 Hall's apparatus consists of a pump, which slowly conveys water to a cistern 

 above each mill, and having a series of sprinkling pipes, connected with an 

 index nicely adjusted, and a stop cock to take off the supply while one is 

 being taken off and another put on. 



Mr. Henry Drayson, of England, has patented an improvement in the 

 manufacture of gunpowder, which consists in dissolving the saltpetre used in 

 its manufacture, and combining the solution with the charcoal and sulphur, 

 and then grinding the mixed ingredients under the mill, in place of grinding 

 undissolved saltpetre with the other ingredients. For this purpose, the salt- 

 petre, having been dissolved by heat in as little water as may be, the charcoal 

 and sulphur in a pulverized state are immediately and intimately mixed 

 therewith. The mixed materials are then ground under the mill, until the 

 combination of them has become sufficiently intimate, and the manufacture is 

 then completed in the ordinary manner. The saltpetre is dissolved in about 

 half its weight of water, and the temperature of the solution raised to the 

 boiling point, but the inventor does not confine himself to this particular 

 temperature or proportion of water. It is preferred to employ saltpetre that 

 has not been melted, but only purified and crystallized. The requisite process 

 of milling may be shortened by first artificially drying off part of the moisture 

 in the mixed materials. 



TO ASCERTAIN WHEN A NEW BUILDING IS DRY ENOUGH TO 



BE INHABITED. 



The Foerstkr Bauzeitung states that the Administration of Jails at Geneva, 

 after a careful examination of the subject, establishes the following rules: 



1. In the newly erected building, sundry rooms, apparently the most dry, 

 and sundry others, apparently the most humid, are to be selected. 



