MECHANICS AND USEFUL ARTS. 



pass through a charcoal filter, which completely deprives it of the disagree- 

 able empyreumatic flavor always possessed by distilled water. Imk'pen- 

 dently of the applications which this apparatus is receiving to the supply of 

 ships with water, it has proved very valuable in readily and continuously 

 producing large quantities of wholesome water for the supply of troops at 

 stations where the only water procurable was unfit for consumption. 



The important subject of the economical supply of well-cooked, and pala- 

 table food to troops in barracks and on active service, which had been consid- 

 erably neglected previous to the late war, has received great attention on the 

 part of Captain Grant; and the results of his labors in this direction have 

 been the production of most efficient cooking-ranges for barracks, and equip- 

 ments for cooking in the field. By the employment of the range, with oven 

 attached, which has been contrived by him, and is used at Aklershott, \Vool- 

 wich, and other military stations, the cost of cooking for a large number of 

 troops eight hundred to one thousand being supplied with food from one 

 range has been reduced to a halfpenny per man per week; and, by 

 further improvements which Captain Grant is just carrying out, it will still 

 be subject to considerable reduction. The food is, at the same time, cooked 

 in various ways, by means of the oven and other appliances. An arrange- 

 ment has been devised by Captain Grant, and used by troops with great suc- 

 cess, for cooking in the field in long cylindrical boilers, which are so disposed 

 over ti-enches dug for the purpose that, Avith a very small consumption of 

 fuel, well-cooked food may be supplied from eight of them, in between two 

 and three hours, sufficient for eight hundred men. These kettles are of such 

 a form that they may also be made to serve the purpose of pontoons in the 

 construction of bridges. 



The subjects briefly discussed in this discourse can only be regarded as 

 examples of the many directions in which every branch of science has 

 recently received application in connection with the military service. 



PROPERTIES OF GUNPOWDER. 



Mr. Fairbairn, F. R. S., has communicated to the Philosophical Society of 

 Manchester the following results of "An Experimental Inquiry into the 

 Effect of severe Pressure upon the Properties of Gunpowder." During the 

 late war, the author received from the government authorities different sam- 

 ples of gunpowder, for the purpose of submitting them to severe compres- 

 sion, in order to ascertain the effect of close contact between the particles 

 upon its explosive properties. At the government works there is no ma- 

 chinery of sufficient strength to give a pressure of more than five thousand 

 to six thousand pounds per square inch; and as it was considered advisable 

 to test the quality of the powder under the influence of greatly increased 

 pressure, the author was requested to compress it in an apparatus of his 

 own, calculated to effect its condensation under a force of more than sixty 

 thousand pounds per square inch. By carrying the pressure in this way far 

 beyond the ordinary limits, it was expected that the precise influence of 

 compression on the properties of the powder would be more clearly and 

 accurately exhibited. 



The samples of powder were placed in a wrought-iron box, and com- 

 pressed by a lever, acting upon them by a solid piston, with a force varying 

 from thirty-eight thousand to sixty-seven thousand pounds per square inch 

 in the different specimens. When taken from the apparatus, the powder 



