392 Scientific Aspect of the International Exhibition. [July, 



The manufacture of aerated waters is always a matter of 

 interest, and the visitor will be well rewarded by a study of 

 the machines and methods exhibited by Messrs. Hay ward, 

 Tyler, and Co., by Messrs. Barnet and Foster, and by Messrs. 

 Fleet and Co. The chief difference in these methods is in 

 closing the bottles. By Messrs. Barnet and Foster the 

 bottle is closed with a marble pressed against an india- 

 rubber welt by the force of the gas, while Messrs. Hayward 

 and Co. employ a wooden plug to effect the same purpose. 



We may class together the peculiar machinery employed 

 in working or crushing stone. First, in catalogued order, 

 there is an exhibit by the Diamond Rock Boring Company 

 of their drills for mining, quarrying, &c. The black hard 

 carbons are fixed in a collar at the end of a tube, and are 

 made to rotate on the face of the rock to be bored. Messrs. 

 H. R. Marsden exhibit a machine for crushing ores or 

 breaking stones, consisting in the application of corrugated 

 powerful jaws to this purpose. But by far the most unique 

 exhibit is the sand-blast of Messrs. Tilghman, which has 

 already been described in the pages of this journal. It will 

 not, however, be uncalled for to give again the principles of 

 this invention. The force employed is the abrading action 

 of minute particles of sand (impelled by a steam or air-blast) 

 when brought into contact with a hard, resisting surface, as 

 that of stone, glass, &c. By covering the portion of the 

 surface which it is desired should remain uncut with a 

 medium having but slight elasticity, as paper, india-rubber, 

 designs may be produced upon the surface, or cut entirely 

 through by continuing the action. The sand is admitted 

 from a hopper into an inner tube surrounded by a steam-jet, 

 the steam being supplied from 55 lbs. boiler pressure. In 

 five minutes three-sixteenths of an inch of marble were cut 

 away. In this process, by means of chromatised gelatine, 

 photographs may be taken and cut into glass. 



We must pass by the silks and velvets, for our time is 

 running short, and there are still the surgical appliances to 

 be seen. These are arranged in the west theatre on the 

 balcony floor of the Royal Albert Hall, and include not only 

 the most modern improvements, but a historical collection 

 extending back to the time of Greek medicine. In this 

 room the instruments, where they are not self-explanatory, 

 need a special medical knowledge for the comprehension of 

 their detail ; and, having stopped with the visitor during his 

 inspection of the Electric Cautery, — in which a platinum wire, 

 raised to red or white, heated by the galvanic current, is em- 

 ployed instead of a heated iron, — we may descend to the 



