1816.] Scientific Intelligence. 83 
patent has been secured by Mr. Collier: a specification of which 
may be seen in the Repertory of Arts for November last. 
‘That you may be impressed with a just idea of this new machine, 
now denominated a Criopyrite (or Fire Ram) I beg to send you an 
extract from a letter, which I received last week, from my_ friend 
Mr. Brunel (under whose directions I am carrying on the new 
works in this yard) ; in answer to a letter of mine about the criopy- 
rite; speaking of which, he informs me, « that nothing is more 
preposterous than the account which has been published respecting 
this new engine; which it is stated, consumes no more than ath 
part of the fuel required for a steam engine of the like power. It 
is true, that an attempt has been made with a view of obtaining all 
_ these advantages, which the Patentee anticipated as certain. Having 
been called upon to witness its action, and to give my aid in direct- 
ing its power, I am‘able to assure you that the new engine, sup- 
posed to possess a power equal to twenty horses, has not yet, to my 
knowledge, moved without some external aid of two or three men. 
The account given out, is therefore a gross imposition ; and as you 
have my sanction, I hope you will do all you can to correct it.” 
The machine at present being in embryo, your correspondent’s 
wish for a. diagram and description, 1 am sorry to say, cannot now 
be complied with. 
If your correspondent will refer to any, or all of the following 
publications, he will find an account, and several tables relative to 
the elasticity and expansive force of steam, of different degrees of 
temperature. Gregory’s Mechanics, vol. ii. pp. 55, 396, &c.: Brew- 
~ ster’s Ferguson, vol. ii. p. 408: Buchanan on Fuel, p. 147, &e. : 
Mr, Dalton’s table of the force of vapour, of each degree of Fahren- 
heit, in 5th vol. of Memoirs of Manchester Society; since repub- 
lished in 6th vol. of Nicholson’s Journal: Article Steam in Ency- 
clopeedia Britannica, &e. &c. 
As to the incrustation on the inside of boilers, I imagine that the 
surest way of preventing it is by using none but water of the purest 
quality: but unfortunately that cannot always be obtained. Having 
been told, that oyster-shells suspended in the boiler would prevent 
all incrustation, I lately tried the experiment. The result was, 
that upon examining the boiler at the end of a month, there was 
found no difference of incrustation, either upon the inside, the 
stone floats, or upon the shells. 
Iremain, Sir, your obedient servant, 
Chatham, Dec. 12, 1815, H. T. Evuicomsr: 
V. Letter from Dr.Rees respecting Mr. Henry's Experiments on 
Bleaching. 
, (To Dr. Thomson.) 
SIR, Dec, 1815, 
Accustomed to the perusal of your publication, { observed in the 
56th number, not without some degree of surprise, a letter ad- 
dressed to me several years ago, and signed Wittiam Henry, 
¥2 
