Letter from Erasmus Darwin to Matthew Boulton, 1765/12/12

Darwin writes to Boulton on steam power and Harrison’s Clock and the proposed Birmingham canal.

Lichfd. Dec 12 – 65

Dear Boulton

I am undone to know what Observations Dr Franklin supply’d you with about your Steam-Engine, besides giving you his approbation, and particularly to hear your final Opinion, and Dr Small’s on the important Question, whether Evaporation is as the Surface of boiling water, or not? – or if it be as the Surface of the Vessel, exposed to the Fire, which I rather suspect – For if you boil Water in a Florence-Flask, you see bubbles rising from the Bottom, these are Steam, as they mount they are condensed again by the cold supernatant Fluid, and their Sides clapping together make that Noise call’d Simmerring. 2ndly When Water boils in the Æolipile or closed Tea-Kettle, what a Quantity of Steam? – is this only as [at] the upper Surface? I humbly conceive not – but as that Surface in contact with the Fire. – Now as a Revd. Canon proves the immortality of the Soul from the Steam Engine, and as the Strength and Activity of Man, or his Momentum, depends on the Quantity of vital Steam rising into the Brain from his boiling blood; so the Quantity of Steam secreted in the boiler of the Steam-Engine is a Question of the utmost Importance in the Creation of this Animal. And I wish yourself and our ingenious Friend Dr Small will communicate to me your joint Opinion on this Head. And withal your Thoughts on the best way of constructing the Boiler for the above Purposes.

I find the People of Cheshire are opposing the Navigation being brought to Birmingham and this Country. I hope you will give this Scheme your assistance. Mr Brindley is in a few Days to wait on Mr Garbet for this purpose to survey a Road for it by ”
“Lichfield nearer than by Tamworth. I desire you and Dr Small will take this Infection, as you have given me the Infection of Steam-Enginry: for it is well worthy your attention, who are Friends of Mankind, and of the ingenious Arts.

Mrs Darwin with her Compl. desires me to mention to you something about [the?] gown She troubled Mrs Boulton with, ? the Lady it belongs to is shortly going to transmigrate to London, and wishes to have the Bill sent along with it.

Mr Mitchel has been a Day or two with me, and I want to explain Harrison’s watch to you – which is very ingenious indeed! – He says Water falling through a Hole in a Vessel has a Velocity, compared to that of Water falling from the Height of its Surface as nearly 7 to 10, is this the Opinion of you Birmingham Philosophers? Hence Bucket Wheels are universally superior to other kinds of Laddles.

Pray write me as long a Letter.


E Darwin