

Nov. 6, 1884] 



NA TURE 



13 



over 28 inches of stemming, and 1 1 inches in the other 

 holes, leaving about 20 inches for stemming. 



The coal-dust is strewn upon the floor of the gallery 

 from the face towards the open end in a layer of about 

 I '17 inch thick immediately before firing the shots. The 

 weight of dust in each ten yards of length is about thirty 

 pounds. It lias been found in practice that, notwith- 

 standing the upward direction of their axes, the shots 

 next the floor produce the greatest disturbance of the 

 coal-dust and give rise to longer coal-dust flames than 

 any of the others. 



In all the experiments witnessed by Mr. Lewis and 

 myself, one shot-hole only, namely, one of the two next 

 the floor, was charged and fired. The charge consisted 

 of 230 grammes of blasting-powder each time, and the 

 tamping was damp clay. Both ends of the branch gal- 

 lery were closed with a double board brattice I 96 inch 

 thick. 



In the first experiment neither coal-dust nor fire-damp 

 was employed, and the flame of the shot was seen 

 through the windows to be a little over 13 feet long. 



ments, some of which were thrown to a distance of 1 1 5 

 feet. The flame was also seen to emerge from the branch 

 gallery to a distance of several yards. The coal-dust 

 remaining on the floor after the explosion was covered 

 with a sooty film, in which coke globules were found 

 embedded. 



The brattice at both ends of the branch gallery was 

 now replaced, and the floor of the main gallery swept 

 clean as usual. In the fourth and last experiment coal- 

 dust from Pluto Mine was strewn on the floor for a 

 distance of 65 feet from the face. A diaphragm of 

 prepared canvas was fastened in the gallery at the point 

 where the space inclosed between itself and the face 

 amounts to 705 cubic feet. 



A volume of 35^ cubic feet of fire-damp was intro- 

 duced into this space, and complete diffusion was effected 

 by beating the air with cloths. The mixture of fire-damp 

 and air thus obtained is not inflammable or explosive by 

 itself, and shows a cap of only l T % inch high on the re- 

 duced flame of a safety-lamp. The firing of the shot 

 produced a flame 190 feet long, accompanied by a report 

 like a thunder-clap. The inner brattice of the branch 

 gallery was broken, and drawn several yards into the 

 main gallery, but the outer one remained intact. 



Some idea of the great force of the two last evplosions 

 may be gathered from the following facts :— An ordinary 

 mine railway, beginning on a level with the floor of the 

 main gallery, extends away from its open end in the 

 direction of its length, and ascending at an angle of 4 . An 

 ordinary mine waggon, loaded with iron so as to weigh 

 I altogether 1 5 J cwt., was standing on the rails at the mouth 

 of the main gallery when the shots were fired. When the 

 third shot was fired, it was driven up along the rails to a 

 distance of 23 feet, and when the fourth shot was fired, it 

 was literally hurled along the railway by the force of the 

 explosion to a distance of 524 feet, being driven off the 

 rails and running on the ground for the last six feet. The 

 boards constituting the end of this waggon next the gallery 

 were broken, but not torn off. A small beam 4 inches 

 square, bolted across the rails at the mouth of the 

 gallery, so as to form a stop for the waggon, was torn 

 from the bolts which held it, and sent flying after the 

 train. Lastly, a shower of stones and debris was raised 

 by the blast which swept out of the mouth of the gallery, 

 and some of the pieces carried upwards of 100 feet. 



The foregoing facts appear to me to be well worthy of the 

 attention of all who have any interest in the prevention of 

 explosions in mines. W . Galloway 



In the second experiment a length of 65 feet of the 

 floor of the main gallery was strewn with coal-dust from 

 Camphausen Colliery in the Saarbnicken mining district. 

 The shot gave rise to a loud detonation, and the resulting 

 flame filled the gallery to a distance of SSJ feet. When 

 the thick black after-damp had been drawn off by means 

 of two of Sorting's exhausters, placed over two of the 

 safety-holes and worked with compressed air, it was found 

 that 'the inner brattice of the branch gallery had been 

 broken, and small globules of coke were observed lying 

 on the surface of the remaining coal-dust. 



In the third experiment a length of 130 feet of the floor 

 of the mam gallery was strewn with coal-dust from Pluto 

 Mine in Westphalia. When the shot was fired, the flame 

 traversed the whole length of the gallery with great 

 . and came out at the open end to a distance of 

 16 feet, being thus altogether 183 feet long. Notwith- 

 standing the entire absence of fire-damp, this was a true 

 explosion of the most violent kind, and the clouds of after- 

 damp which streamed from every opening darkened the 

 air in the neighbourhood of the gallery for two or three 

 minutes. The brattice at the inner end of the branch 

 gallery had not been replaced before this experiment, 

 and the one at its outer end was broken into small frag- 



FLOWERS OUT OF SEASON 



THE untimely flowering of trees and shrubs, like the 

 occurrence of the extraordinary gooseberry, is a 

 subject which crops up at such regular intervals as almost 

 to belie the epithet applied to it. Nevertheless, the very 

 frequency of the comment is an indication that the matter 

 is ill understood. 



The ordinary time-rate for the production of new cells, 

 new leaves, new flowers, and so on, varies as we see within 

 wide limits. Equallv obviously those limitations are im- 

 posed by the conjoint effects of inheritance and of external 

 conditions, such as climate or food, or both. An annual 

 plant rushes through its life in hot haste as it were : save 

 and except in the seeds of such plants there is compara- 

 tively little building up or maturing of new tissues to be 

 done, and proportionately still less stores of potential food 

 to be accumulated. If, on the one hand, the requirements 

 of such plants are less than in the case of perennials, 

 their exigencies are, on the other hand, more pressing. 

 What they take from the soil, or atmosphere, what power 

 they derive from solar light and heat, must be got quickly or 

 not at all. One illustration of this is afforded by the paucity 

 of annual species in the Arctic regions or at high altitudes. 

 Neither heat nor light is absolutely deficient in such situa- 



