518 
POPULAR SCIENCE REVIEW. 
MECHANICAL SCIENCE. 
Rock-Boring Machinery. — Mr. Downie has communicated to the Institute 
of Engineers, in Scotland, a paper descriptive of the various machines pro- 
posed and adopted for boring rock, either with a view of superseding blasting 
operations, or to take the place of hand labour in boring the blasting holes. 
The most novel and interesting part of this paper is the description of the 
working of the machine of Mr. G. Low employed at the Dublin Water 
Works. The peculiarity of this machine, which bores holes preparatory to 
blasting, is that the steam or air cylinder is stationary, the tool being tele- 
scopic. The tool is propelled by a self-acting arrangement according to the 
speed at which it is actually cutting. In trials it bored granite at the rate 
of fourteen and a half inches in seven minutes, and three inches in fifty-five 
seconds. The average rate at which it bores the rock at the Dublin Water 
Works Tunnel, Eoundwood, is one inch per minute. The rock is composed 
of green hornblende, with white quartz veins, and is so hard that miners have 
sometimes used from twenty-four to thirty-six tools to complete one hole, 
twenty-four inches deep. The machine strikes 500 to 600 blows per minute 
on the boring-tool. The following table gives the results of a series of trials 
at Eoundwood. 
(1) 24i inches 
in 11 minutes 10 seconds ... Two tools. 
(2) 19i 
14 
0 
„ ... Two tools. 
( 3 ) 
9 
5 
55 
„ ... Two tools. 
( 4 ) 
4i 
2 
10 
„ ... One tool. 
( 5 ) 
9 
7 
35 
„ ... One tool. 
(6) 
9 
V 
5 
5 ? 
25 
„ ... One tool. 
Mackay Gun. — A defect has been discovered in the Mackay gun under 
proof at Woolwich. One round was fired with a charge of 50 lb. of powder. 
The gun weighs 10| tons. 
Adhesion of Locomotives.' — Mr. Bridges Adams has invented a plan of 
increasing the adhesion of locomotives by the use of friction-wheels, trans- 
mitting power from the periphery of the driving-wheels. Thus, in an eight- 
wheeled locomotive, with the two centre pairs of wheels coupled in the 
ordinary way, friction-wheels are placed between the fore pair of drivers, and 
the leading-wheels and the back pair of drivers and the trailing-wheels. The 
whole weight of the engine is thus made available for propelling the train. 
Cupola Furnaces. — At Messrs. Woodward’s foundry in Manchester, the 
ordinary fan-blast for cupolas has been superseded by a steam jet, acting so 
as to produce a vacuum in the cupola. It is proposed also to surround the 
upper part of the cupola by the boiler supplying steam to the jet. The plan, 
as far as it has been tried, is said to have economised fuel, and to have pro- 
duced better castings. 
Wear and Tear of Steam Boilers. — We have received from Mr. F. A. 
Paget, C.E., a copy of a paper read before the Society of Arts on the wear 
of steam boilers, in which the entire series of complex causes affecting the 
durability of boilers are considered under the following heads : — 1st, the 
direct effects of the pressure of the steam; 2nd, the mechanical effects of 
heat ; 3rd, the chemical effects of the fuel ; and 4th, the chemical effects of 
