My dear Dyer,

I have a very strong opinion that it would be the greatest possible pity if the Phys: Lab., now that it has been built, were not supplied with as many good instruments as your funds can possibly afford.¹ It is quite possible that some of them may become antiquated before they are much or even at all used. But this does not seem to me any argument at all against getting them, for the Laboratory cannot be used until well provided; and the mere fact of the instruments being ready may suggest to some one to use them. You at Kew, as guardians & promoters of Botanical Science will then have done all in your power, & if your Lab. is not used the disgrace will lie at the feet of the public. But until bitter experience proves the contrary I will never believe that we are so backward. I should think the German laboratories would be very good guides as to what to get;² but Timiriazeff of Moscow who travelled over Europe to see all Bot. Labs, & who seemed so good a fellow, would I should think give the best list of the most indispensable instruments.³ Lately I thought of getting Frank or Horace to go to Cambridge for the use of the Heliostat there;⁴ but our observations turned out of less importance than I thought; yet if there had been one at Kew we should probably have used it & might have found out something curious. It is impossible for me to predict whether or not we should ever want this or that instrument, for we are guided in our work by what turns up. Thus I am now observing something about geotropism, & I had no idea a few weeks ago that this would have been necessary.⁵ In a short time we might earnestly wish for a centrifugal apparatus or a heliostat. In all such cases it would make a great difference if a man knew that he could use a particular instrument without great loss of time. I have now given my opinion, which is very decided whether right or wrong & Frank quite agrees with me. You can of course show this letter to Hooker⁶

Yours very sincerely | Charles Darwin.