From Horace Darwin to G. H. Darwin 13 February 1881

Dear George

I have just read Idas letter & I will give you a little information about the pendulum. The tube is done the window in, but we don’t know whether it will hold water. Mr. Gordon thinks that we can make it water tight by putting 2 or 3 rings of felt under it & bolting it down straight onto the top of the stone, with no circular groove this would be much the least trouble & I think we had better try it. The instrument is v. nearly done, & I will try & get it into working order soon, & get on with the whole thing as much as I can. I have not hung the pendulum up yet in the tube, there will be a good deal of work for me to do to it with the secondary pendulum & all. The shop is going on very flourishing I think, I think it has (any how as yet) been a very good thing for me joining, it has given me so much more interest in every thing connected with it. Roy still continues to give a good deal of work. The Cathetometer is getting on well, but it is not in a fit state to see how it works yet, it will be interesting when that state comes & perhaps dissappointing. I am at work now improving the Artificial Respiration. We want to get it to go silently, & with less pressure of water, & also to give it a handle so that if the water pressure goes off for a few minutes it can be worked by hand. Im at work at this now. There is lots for me to do, in fact rather too much. Our London visit was rather a failure, Ida was laid up most of the time. Effie was good for her, but after all that has happened I can’t feel at ease with her, so it is not pleasant for me & I think it is less pleasant for her. I expect you will have heard some rumour of this as I hear Down is furious with her & I am afraid I sympathise too, but it is no good growling so I will stop. We will have a bender at the old pendulum when you come back.

Yours affec. | H. Darwin.