1866. | Mining, Mineralogy, and Metallurgy. 595 
being the money-worth of the productions drawn from our rocks. 
To this must now be added the mineral oils produced in this country 
from the bituminous shales and cannel coal. The value of those 
mineral oils has not been given by Mr. R. Hunt, but we have every 
reason for believing that it does not fall short of three millions 
sterling. If therefore to the above we add this and the estimated 
value of our clays, bricks, slates, and building stones, we cannot 
estimate the mineral wealth of the United Kingdom at the present 
time at less than fifty millions sterling. 
The necessity of working our collieries with economy is forcing 
—more and more—upon the attention of our coal proprietors the 
application of machinery for cutting coal. We have already de- 
scribed several of those machines; some of which are, we believe, 
doing their work effectively. We cannot afford space in this Journal 
for any long descriptions of machines, howsoever ingenious they may 
be, which have not received the test of a sufficiently long experience 
in actual working, to determine their merits. 
Our attention has been called to a new hydraulic coal-cuttng 
machine manufactured by Messrs. Carrett, Marshall, and Co., of 
Leeds. The machine is described as automatic, of three-horse 
power, and cutting at the rate of fifteen yards per hour, four feet 
into or under the coal, and at any height or angle, and at once 
going over. It uses im this work thirty gallons of water, making 
fifteen strokes a minute at a pressure of about 300 Ibs., the cutting 
tools displacing only three inches of the coal so undercut. There 
are doubtless many advantages in the use of hydraulic power rather 
than that of air. In one case the power can be conveyed without 
loss; in the other the loss of force is great. This machine was 
highly spoken of at the recent Meeting of the British Association. 
Messrs. Pigott and Farrar, of Barnsley, are said to have made 
some great improvements in a machine for pumping or compressing 
air for working coal-cutting machines, or for propelling engines of 
any kind used in a colliery. We also hear of a new coal-cutting 
machine, the joint invention of Mr. Gillett, mechanical engineer, 
and Mr. E. Beecher, the colliery engineer at the Thorncliff and 
Chapeltown Collieries. When these machines have had a sufficient 
trial we may again return to a consideration of them. 
MINERALOGY. 
M. Pisani having received a black Spinelle from Haute-Loire, 
through the attention of M. Bertrand de Lorn, has submitted it to 
careful examination, and communicated the results to the Academy 
of Sciences of Paris, through M. Ste. Claire-Deville. This black 
Spinelle has been found principally in the Haute-Loire, but it has 
been met with in Cantal and the Puy-de-Dome. It is found in the 
