"I shall be obliged if you can find space for the accompanying translation of an interesting letter which I have received from a German lady, who with very homely appliances has arrived at valuable results respecting the behavior of contaminated water surface. The earlier part of Miss Pockels' letter covers nearly the same ground as some of my own recent work, and in the main harmonizes with it. The later sections seem to me very suggestive, raising, if they do not fully answer, many importnat questions. I hope soon to find opportunity for repeating some of Miss Pockels' experiments." RAYLEIGH
My Lord, - Will you kindly excuse my venturing to trouble you with a German letter on a scientific subject? Having heard of the fruitful researches carried on by you last year on the hitherto little understood properties of water surfaces, I thought it might interest you to know of my own observations on the subject. For various reasons I am not in a position to publish them in scientific journals, and I therefore adopt this means of communicating to you the most important of them.
First, I will describe a simple method, which I have employed for several years, for increasing or diminishing the surface of a liquid in any proportion, by which its purity may be altered at pleasure.
A rectangular tin trough, 70 cm long, 5 cm wide, 2 cm high, is filled with water to the brim, and a strip of tin about 1 1/2 cm wide laid across it perpendicular to its length, so that the under side of the strip is in contact with the surface of the water, and divides it into two halves. By shifting this partition to the right or the left, the surface on either side can be lengthened or shortened in any proportion, and the amount of the displacement may be read off on a scale held along the from of the trough. ...."
Yours faithfully, (Signed) Agnes Pockels Nature, 43, 437 - 439, '1891'.