Autograph letter signed ("affectionately yours M. I. Bl.") to I. K. Brunel ("my dear Isambard"), 4 integral pages with diagram and characteristic underlining, 8vo, 13 Decem. 1841.

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Autograph letter signed ("affectionately yours M. I. Bl.") to I. K. Brunel ("my dear Isambard"), 4 integral pages with diagram and characteristic underlining, 8vo, 13 Decem. 1841.
A detailed letter, demonstrating the continuing very close working relationship between father and son, while dealing with the vital need to keep water from the tunnel at the critical stage when the two shafts at either end were joined.
"I cannot go to the Board today without seeing you first.
"I may say for your information that Drawings are being made and will be forward enough to show what must be done for making use of the Company's Pumps that are at Dawkin's.
"The South shaft (Rotherhithe) is very forward, with the 9ⁱⁿ lining and will be ready on Wednesday ---- The steam engine cannot however be removed until another apparatus is in a fit condition for the pumping Service.
"The average quantity of water now taken up (on the average of the last 16 months) is 460 gallons per minute, and for the last 11 days 467 -- for the month of November last 463. More than ³/4 of that quantity is admitted through plug-holes that may be and are to be closed when the body of the Tunnel is completely connected with the Shaft -- Every thing goes on very well there for the emission of the 12 Frames and for the soundness of the junction.
To effect the Pumping, I contemplate doing it through the Wall that is before us and fitting two plunger Pumps within the first Crop Arch. This can be done easily -- and inclosed afterward. [diagram]
As to the ultimate object, you will find that Hague's plan is the best for us tho' it may not be the most economical compared with well fitted pumps acting in a direct line. And by the following the plan which I have just delineated, the company will have at any time the option of substituting the above viz Hague's.
Upon this plan, my dear Isambard, I can take two of our own pumps (12ⁱⁿ Plungers) and leave the present Company's Pumps for any other service -- for I am persuaded that we shall not have 100 Gallons to pump up but even 200 may be raised in this manner ---- At one time, after a most Terrific influx of water which lasted nearly a fortnight, we had but 87 Gallons for two months and 107 for several months after ---- but afterward, I can account for the encrease to 2. and 300 G. by the neglect in the service of the abutment screws.
The post-script implies that Isambard has been asked to design the stairs for the Rotherhithe shaft, then reverts to the pumping issue. "You will have to make some modification in the plan of the Stairs for the Rotherhithe Shafts in consequence of difference of diameter ---- It is not possible to give possession of both shafts at once -- The transaction of power from a Steam Engine to the Pumps of miners is frequently affected by Rods -- there cannot therefore be any objection to my plan. Send me a reply ---- for our meeting."

Lot Essay

The "abutment screws" or abutting screws, mentioned in the final paragraph, were two large screw jacks that drove forward the shield. Rearward thrust was transmitted first through the poling screws to the frame and then through the two screw jacks to the leading edge of the tunnel brickwork.

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