TRANSACTIONS OF THE SECTIONS. 201 



The other occurred at the North-Unst Lighthouse, -which is built on a rock, 

 ■whose height is 190 feet ahove high water, and presenting an almost perpendicular 

 face to the sea. In this case, during a heavy north-west gale, a quantity of 

 water was projected upwards sufficient to overthrow the boundary walls and force 

 open the door of the house. 



With regard to the form of jet produced by a subaqueous explosion near the 

 surface, I had the opportunity, a short time since, of witnessing an experiment 

 made by Professor Abel at the Eoyal Arsenal at Woolwich. 



The explosive used was compressed gun-cotton. The jet on this occasion rose to 

 a great height, reminding one of the great Crystal-Palace fountain, and it was 

 remarkable from the complete vertically of its centre line of force, and from the 

 resemblance in its pine-tree form to the jets of Niagara. 



On Recent Experiments in Telephony. By Professor Graham Bell. 



On the Plymouth Waterworks. By G. D. Bellamy. 



On the Removal of Sand Bars at the Mouth of Harbours. By C. Bergeron. 



On the Circulation of Hot Water in Buildings. By F. J. Bramwell. 



Lode Mining in the West of England. By J. H. Collins, F.G.S. 



The author restricted his remarks to the mining of lodes properly so called, 

 Without referring to the general geology of the district or to the mineral deposits 

 other than lodes. He also left untouched the questions of drainage, ventilation, 

 and ore-drainage. He defined a lode as a mineral deposit occupying a fissure in the 

 ground or the rocks on either side in its immediate neighbourhood, and containing 

 metallic minerals in greater or less proportion, and the rich parts as being those 

 parts of a lode which are sufficiently rich to pay for working. 



He stated that the same lode might be, and often was, worked at the same time 

 by several companies, and that it might yield ores of different kinds, as tin and 

 copper, either mingled together or at different depths; that the "bearing" of best 

 tin- and copper-lodes was approximately east and west (magnetic), the average 

 inclination or underlie 70°, the variations in width from a mere line to 20 or 30 

 feet, the average width less than 4 feet, and the average produce, even of the rich 

 parts, taken as a whole, was less than 4 per cent, for copper-ores, and less than 2 

 per cent, for tin-ores ; that copper-lodes in groimd of moderate hardness were 

 generally richer than those in very hard or very soft ground; that the more 

 vertical parts of lodes were generally richer than the less vertical, the wider richer 

 than the narrower, the lodes dipping towards granite richer than those dipping 

 away from it ; but that there were many exceptions to all these generalizations. 



He then compared a lode to a steep or rearing seam of coal, and stated that it 

 was in general subject to all the irregularities of such a seam with other irregularities 

 superadded. 



He then described in detail the modes of discovering lodes and laying out lode- 

 workings, and the mode of sinking shafts, driving levels, &c, with the cost, under 

 ordinary and extraordinary conditions, and the comparative advantages of downright 

 or vertical and inclined shafts. 



He then described the methods of timbering shafts and levels &c, and the 

 different classes of workmen employed in the mines, with the nature of the 

 different contracts under which they worked, with their advantages and disad- 

 vantages, also the arrangements for supervision. 



1877. 16 



