Metropolitan sewers. 1 Greek Street, 22nd June, 1849. Sir.

  • Lovick, Thomas.
Date:
[1849]
Catalogue details

Licence: Public Domain Mark

Credit: Metropolitan sewers. 1 Greek Street, 22nd June, 1849. Sir. Source: Wellcome Collection.

    2/2 (page 2)
    Taking the sectional area (—100 inches) of the larger flow (= 150 cubic feet per minute), and the mean velocity generated = 3-6 feet per second, or 2*4 miles per hour, I assumed the sectional area required to accommodate the mean flow of house-sewage only (for the day and night) for the whole of the Metropolis to be proportional to the sectional area of the greatest -observed flow on water-days, and equal mean velocities in each, and I found that a pipe 35f inches, or less than 3 feet in diameter, placed under similar circumstances, would be ample for the purpose ; a deduction based upon upwards of 200 actual observations, and strictly in accordance with every collateral fact and observation within my knowledge. As I wished entirely to avoid all results not based upon actual observation, I did not give you any theoretical deduction of the exact required size, but a size which it was certain (on the data given) would be a maximum. Had I calculated the acceleration of velocity due to the aggregate mean flow of the Metropolis from the observed accelerated velocity accompanying each increase of flovv—an element I should have been perfectly justified in using,—a size very much smaller than that stated by me would have resulted. Of course I did not for a moment assume, neither did you so understand it, that the results of the Earl-street experiments would truly represent the whole of the other parts of the Metropolis, except as these were assimilated to it, as this was a point to be ascertained only by experiment. I am certainly greatly surprised that Mr Phillips, in his letter to the Court of 21st inst., should have so misconstrued your statement, as he must have known from my explanation to him some few days since its exact nature; but the absurdity of the construction put upon it is, in my opinion, its own refutation, and must be so viewed by every unprejudiced mind, as you expressly excluded the main elements involved in it. I am, Sir, your most obedient servant, THOMAS LOVICK. E. Chadwick, Esq., C.B.