280 ANNUAL OF SCIENTIFIC DISCOVERY. 



GNEISS AND SURPENTINE FORMATIONS. 



LEONARD and BRONX'S Jahrbuch state that they have observed 

 gneiss associated with conglomerate, and great veins of gneiss travers- 

 ing gneiss. These facts have been verified by the discovery of similar 

 phenomena in other countries, and gneiss is now divided into the 

 following formations : 1, Primary Gneiss, that associated with certain 

 granites, and forming the fundamental or oldest formation of the 

 crust of the earth ; 2, Transition Gneiss, that which rests upon transi- 

 tion rocks, as greywacke, clay slate, and old red sandstone, and even 

 alternates with them ; 3, Secondary Gneiss, this formation rests upon 

 Has, and is well seen in Switzerland. We have no intimation that 

 gneiss has been met with in the tertiary group. 



Many years ago, Jameson noticed the gradual transitions from trap 

 to serpentine, both in Germany and Scotland. Very lately the cele- 

 brated Rose, of Berlin, has illustrated this view in a very interesting 

 manner. 



ON THE EVOLUTION OF GAS IN WALLSEND COLLIERY, ENG. 



PROF. PHILLIPS at the British Association remarked that the 

 Wallsend Colliery was one of the numerous coal mines in Yorkshire 

 which have been rendered remarkable for the frequent explosion of 

 the inflammable and noxious gas with which they are filled, and the 

 loss of life which has in so many cases been the consequence. In 

 every coal-pit there are two shafts, one of which serves to admit the 

 pure air, whilst the foul gases are made to escape by the other. The 

 ascent of the foul gases is frequently facilitated by creating a draft by 

 fires placed near the bottom of one of the shafts. The coal is arranged 

 in perpendicular layers, between which the gases exist in a highly 

 compressed state. In order to detach these layers with the least pos- 

 sible danger, it is usual to cut through them endways, by which means 

 the gases are allowed to make their escape at once from a considerable 

 portion of the coal. A district of this colliery, covering about fifty 

 acres, was effectually walled up, in consequence of the immense dis- 

 charge of gas that was continually taking place. A pipe was led 

 from this enclosed portion up through the mine and for forty feet 

 above the surface, and from this pipe there has been a constant dis- 

 charge of gas for the last eighteen years. This gas has been inflamed, 

 and in the roughest and most stormy weather it has burned without 

 intermission ; and were it as rich in naphtha as ordinary carburreted 

 hydrogen, it would illuminate the country for miles round. Two 

 water-pressure gauges were fixed to the brick walls, one at the surface 

 of the earth, and the other at the bottom of the mine, and the results 

 were that, whilst the pressure in the mine was only 9-10ths of an inch 

 on an average, that at the top of the pit was upwards of four inches. 

 From observation in these mines, it is seen that discharges of fire- 

 damp, governed by atmospheric pressure, take place before being indi- 

 cated by the barometer, and that, as an indicator that instrument can- 



