Robert Mallet to Faraday   9 March 1857

Delville, Glasnevin | Co Dublin | 9 Mar 57

My dear Sir

In relation to some professional questions - it is a matter of some importance to me to obtain an Estimate of the average force of expansion of the fire damp in Coal seams - as it issues from the “Blowers” say in inches of Mercury.

From your connection in time past with the subject of Colliery explosions¹ it has occurred to me that you could probably give me some approximate data[.]

There is neither time nor opportunity for making any experiment.

The probable theoretic maximum pressure of an expanding “Blower”. I take to be that due to the liquid gas, at the moment it becomes gaseous, and at the temperature & pressure due to the coal seam or locality?

I think I may count upon your not grudging a crumb of knowledge - though I feel that it demands a very important object to justify any trespass upon your time, the value of which is not to be counted in money - against which in truth you have never weighed it[.]

with much esteem | my dear Sir | faithfully yours | Robert Mallet.

Mr Faraday Esq FRS. | &c &c &c