1874.] Mr. W. Galloway on Safety-Lamps. 449 



The next experiments were on a larger scale. Through the kindness 

 of Mr. Carrick, the City Architect of Glasgow, part of a new sewer in 

 North Woodside Eoad was placed at my disposal ; and Mr. Foulis, the 

 manager of the Corporation G-as-Works, caused a pipe to be led into it, 

 and provided a liberal supply of gas. Figs. 4, 5, & 6, Plate VII., are 

 sections of the part of the sewer in which the experiments were made : 

 fig. 4 is a plan section through the widest part, fig. 5 is a vertical cross 

 section showing the dimensions of the sewer (6 ft. x 4 ft. are the greatest 

 measurements), and fig. 6 is a vertical longitudinal section through the 

 highest part. Part of the sewer is a tunnel in solid rock (the diagonal 

 shading in fig. 6 shows the position of the rock), and part of it is built in 

 brickwork through the surface-drift. The length that was available for 

 the experiments is comprised between the point A, where there was a 

 wide shaft to the surface, and the point C, where I caused a wooden 

 partition to be set up to prevent the draught of air from affecting the 

 lamp. B is a manhole, 3 ft. 6 in. x 3 ft. 9 in. at the bottom, and 23 in. 

 square at the top ; it was covered by two stones, each about 2 in. thick, 

 with a space about 1 in. wide between them across the middle of the top 

 of the manhole. The safety-lamp part of the apparatus (fig. 1, Plate VI.) 

 was set upon a board fixed across the sewer at the point L, at a height of 

 2 ft. 8 in. from the deepest point. 



I made a large number of experiments here, but it will be sufficient to 

 give only the principal results. The shots were fired from the same 

 pistol that was employed in the former experiments at the distances from 

 the lamp indicated by the figures below fig. 6, Plate VII. ; they were 

 nearly all fired towards the position of the manhole B. Each measure 

 of gunpowder weighed "273 gramme ( = 4*213 grains). The number 

 of measures given below, corresponding to the distances from the 

 lamp at which the shots were fired, are those by which the flame 

 was passed ; and it is to be understood that at each distance a charge 

 containing one measure less was generally insufficient to effect the 

 purpose. 



(1) Between C and L : 



At 27 ft. 5 measures = 1-365 gramme 

 54 ft. 8 2-184 grammes 



81 ft. 10 = 2-730 

 96 ft. 12 = 3-276 

 109 ft. 14 = 3-822 



One experiment was made with the pistol pointing towards the roof at 

 an angle of 70 to the axis of the sewer ; the distance was 109 ft., the 

 charge 20 measures, = 5-460 grammes; the muzzle of the pistol was 

 1 ft. 6 in. from the floor, and the firing was effected by drawing a cord. 

 The flame passed through the wire gauze, and ignited the gas on the 

 outside. 



