From G. H. Darwin [2 December 1869]1
14 Arlington St. | Piccadilly
My dear Father,
After grinding away for some time at the calculation of the red & white animals it suddenly occurred to me that I could find without any bother at all the ratio of the reds to the browns at any period, that is to say the percentage of the whole no of animals existing at that period which are brown. In fact the death rate has no effect whatever on this percentage, for this is the very meaning of the death rate being the same for browns & reds. If this is all you want I can do it in five minutes, but if you want the actual numbers of reds and browns at each period—I can easily calculate it, I had in fact actually done it for the first period when I perceived this thing wh. had been staring me in the face all the time.—2 Will you write me a line to Cambridge & let me know what you want. I have just been dining here with a man that I have known for a good time at Cambridge called Hammond, & he tells me that his Uncle was a lieutenant on the Beagle.3 As I thought you might like to know what had become of him I found out that he is banking down in Norfolk or Yorkshire I forget which.4
I also find that he knows Sullivan a little.5 Again I fd out today that Whiteford (a man at Tathum’s) old Col. H Smith of Plymouth’s grandson knows Mrs Clem. Wedgwood very well;6 how marvellously small the world is. I am going to take a holiday on Saturday & Monday & I am going down to Camb. tomorrow night.
Balfour & Strutt I there & it is the last of Balfour that I shall see at Camb. as he has just been in for his degree & goes down next term.7 I went to Nilsson’s concert last night & thought it extremely good.—8
Your affectionate Son | G. H. Darwin
Discusses some calculations which he is doing for CD on the ratios of red and brown colouring in some animals.
Please cite as
Darwin Correspondence Project, “Letter no. 7158,” accessed on 1 October 2016, http://www.darwinproject.ac.uk/DCP-LETT-7158