Scientific Intelligence.— Arts. 891 
lifted 41,058,808 pounds, one foot high, with a load of 71,658 
pounds per inch ; and several others, lifting between 30,000,000 
and 40,000,000 of pounds, at various loads, per inch. There 
are also reported, twelve steam-engines employed in drawing 
ores, and four in stamping ores, thus making a total of sixty- 
nine reported steam-engines employed in the Cornish mines. — - 
It should, however, be remarked, that these reported steam- 
engines are by no means the total numbers of steam-engines em- 
ployed in Cornwall ; and there are, besides, many water-wheels of 
large diameter, employed in pumping, &c. as well as pressure- 
- engines , working by the power of columns of water, employed 
as steam is, in the steam-engines. We are just now informed 
of a water-wheel erecting at the Wheal Harmony Mine, of fifty 
feet in diameter, and which is intended to assist in working the 
pumps employed in freeing that valuable mine from water.— 
Journal of Arts. 
42. Paste for sharpening Razors.— Take a quantity of slate, 
wash it well, pound it in a mortar, and pass it through a very 
fine hair-sieve ; mix some of this powder, first with well-water, 
and afterwards with olive-oil, to the consistence of fat. Put 
some of this paste upon a common razor-strap after it has been 
properly cleaned, so as to remove all foreign bodies from it. 
Pass the razor from right to left, as usual, ending with raising 
the back a little, and a perfect edge will be obtained. 
48. Manufacture of Red Crayons . — The red crayon, and its 
use, are two well known in daily life to require any thing to be 
said of them. The preparation of the red crayon, which is best 
adapted for painting, is less known. The following is the man- 
ner in which it is performed : A quantity of hematite is pound- 
ed in a porphyry mortar, with filtered water, until it be extreme- 
ly divided, so as to form an impalpable powder. This powder 
is again diffused through a quantity of water sufficient to allow 
the mixture to pass through a fine sieve, placed above a large 
vessel filled with water. The liquid holding the hematite in sus- 
pension is then agitated ; and, after this, allowed to rest four-and- 
twenty hours. At the end of this time, there is formed at the 
bottom of the vessel a deposit of hematite, in the form of a very 
fine powder : the water is cautiously decanted from it. To form 
crayons of this impalpable powder, a uniting substance is neces- 
