C2 ANNUAL OF SCIENTIFIC DISCOVERY. 



these serve to hold the twist given to the blank. After a blank is 

 twisted the clamps open, the blank is withdrawn, and the twist- 

 ing-spindle returns to its starting-point. 



After twisting, the drills are centred and rough ground, then, 

 hardened by heating in a lead bath and cooling in cold water, 

 next tempered in an oil bath, and finally finished by grinding to 

 a standard gauge. 



The main features in this method, to which it was desired to 

 direct attention, are the forging and twisting, in contrast to 

 cutting from the solid bar. One of the principal difficulties, in 

 carrying out the new system just described, was getting the 

 blanks forged, accuracy being essential ; this difficulty overcome, 

 the benefits became manifest. Recent experiments have shown 

 that, in shaping metals, nothing is of greater importance than at- 

 tending to the " flow of the metal." Every particular shape into 

 which a bar of iron or steel is forged having an arrangement of 

 the particles which compose it peculiar to itself, any departure 

 from this natural arrangement is prejudicial. By forging and 

 twisting these drills, this law is paid the fullest attention to, each 

 drill being finished, so far as shape goes, before a single particle 

 of metal is cut from it. 



By way of reward for attention to this natural law, the number 

 of drills lost from water-cracks, in hardening, is inappreciable as 

 affecting the cost of production. Scientific American. 



THE ROYAL ALBERT HALL OF ARTS AND SCIENCES. A MAG- 

 NIFICENT SYSTEM OF HEATING AND VENTILATION. 



The subject of heating and ventilation is one of ever recurring 

 interest, and of universal importance. We, therefore, copy 

 from "Engineering '' the following description of the apparatus 

 employed in the immense Royal Albert Hall, in London, one of 

 the largest public buildings in the world : 



When it is considered that the Albert Hall of Arts and Sciences, 

 now in course of erection at South Kensington, is to accommodate 

 about 8,000 persons seated, the magnitude of the arrangements 

 for preserving an equable temperature and a pure atmosphere 

 will be realized. The capacity of the hall amounts to 5,000,000 

 cubic feet, so that the warming and ventilation caused the com- 

 mittee some anxiety, and they invited a limited number of engi- 

 neers to send in plans for effecting those objects. The various 

 plans submitted were carefully considered, and it was finally 

 resolved to adopt that of Mr. Wilson W. Phipson, Assoc. Inst. C. 

 E., which is now being carried out under his immediate superin- 

 tendence. The main points by which any arrangement had to be 

 governed were economy in warming, and a satisfactory combina- 

 tion of this process with that of ventilation. The heating-power 

 determined on by Mr. Phipson consists of an arrangement of dis- 

 tinct coils of hot-water pipes, placed in 3 air-chambers. One of 

 these chambers is carried under the main corridor, a second runs 

 beneath the seats of the amphitheatre stalls, whilst a third passes 

 under the arena. These 3 chambers are connected with 2 fans, 



