From J. Bonham Carter to Horace Darwin 9 July 1876

My dear Horace

I was very much pleased to get your letter the other day, and fully recognize the duty I owe you: until now, however, for the last 2 weeks, I have been incessantly on the move, so have had no time for writing and even now I am driven nearly crazy by mosquitoes.

I cannot remember whether I wrote to you before starting, to tell you of my departure: if I did not, I certainly did wrong, but when the plan was made I had so little time (only thirty hours) to get ready, that I had no time to think of anything else.

As I am sure you will believe, I was awfully sorry to leave Erith and to end, probably for good, the days of our companionship in lodging: speaking for myself I realize more than ever how pleasant they were, and that I at least was a gainer by them. I always felt rather ashamed of running away and leaving you alone, but it had to come sooner or later and your then indefinite absence from Erith made it all the easier for me: I think I regretted leaving for Robson's sake almost most, he appeared so fearfully downhearted at the prospect of being there without either of us.

I am very sorry indeed to hear that your planetary arrangement is a failure: I suppose you think now that it ought to have been sufficiently obvious before that it would not act, but that, at least, is a question on which you will be sure not to flatter yourself, and I quite agree with you that the design itself was cute without being complicated.

I shall come down to see you at Erith as soon as I come back, I hope, as I shall have lots to tell you and ask you about: I shall certainly have lost no interest in your spanner or dynamometer, and shall hope to have some crude ideas on a new kind of telegraph—a modification of Thomson's syphon recorder—to communicate in return: talking about telegraphy there are some wonderfully cute things in that line in the Exhibition, which I should have heard nothing of if Sir W. T had not been judge of them: as for instance an automatic morse sender & receiver capable (as I saw myself) of transmitting 1050 words in 57 seconds between New York & Philadelphia, another instrument which by making use of tuning forks as contact breakers at the sending end of a wire can transmit ""electrical vibrations"" through that wire which shall be singled out by reeds tuned in unison with the forks, each reed (when the notes are chosen so as to be out of harmony) sounding only when its own particular fork is thrown into circuit, and thus enabling a theoretically large number of different signals to be sent at once: but the cleverest thing of all was a speaking telegraph *P [diagram annotated with "A", "B", "B'", "A'", "line wire", "ground" and "ground"] *Q A A' are two chambers, open at one end and closed at the other end by a flexible diaphragm carrying the armatures of the electro-magnets B.B': the rest of the picture I hope will explain itself: the circuit through line and magnets is always closed and the armatures a slight distance from the latter Suppose now that the sender speaks into A and the receiver has his ear against the aperture of A': the armature opposite B will vibrate to the tones of the voice, and its movement will by induction produce similar vibrations in the intensity of the current: these vibrations will in turn affect the armature opposite B' and the diaphragm which carries it finally transmitting the sound reproduced at A', to the ear: in an instrument in which the receiving apparatus was slightly varied, tho' the same in principle, I distinctly heard words as also did Sir W. T, though the inventor claims for it only that it is in the embryo at present.

However more of this when we meet.

I am at present travelling with Murray, eldest son of the London publisher, and a great friend of my cousin, A Nicholson, and also brother of a man I knew at Cambridge: we met at Philadelphia and have hitherto managed to hit it off pretty well together.

We have been to Washington, Cincinnati, down the Ohio to Louisville, Mammoth Caves, Chicago, Milwaukee, & Prairie du Chien: and we are now on our way up river to S^t. Paul: thence we go by train to Duluth on Lake Superior, mining districts of Marquette, Detroit, Niagara, Montreal, possibly Quebec, Saratoga Newport, New York. Murray will then have to go home and I hope my cousin will come out and join me in a trip to San Francisco: I wont enter into details now as you must have heard everything of interest that I could tell you from Frank, but we will talk about it when we meet: I will only say that, actual travelling barred, I am enjoying myself immensely.

I met a gentleman by name Rosengarten at Philad'a: he knew all of you and had been at Down: I thought him rather a bore, tho very kind in intention

And now, hoping that you are really stronger again and that William has recovered completely from his accident, I must end, and wishing to be remembered to all your people, to Robson and to anybody at Erith who cares to hear of me, I remain

yours ever | J BonhamCarter

I came over with the following judges: Sir W. Thomson. Sir John Hawkshaw, M^r Barlow & Capⁿ. Douglas Galton: Sir John was the only one quite well throughout the voyage, and has always been extremely genial & good natured: of Sir W. Thomson (whom, with Lady T, I like immensely) and of his various Lodges I shall have much to say when we meet.