The Open Sea - The World of Plankton / Alister C. Hardy

London: Collins. 1956. Out of print.

Published in 1956 as part of Collins's acclaimed New Naturalist series, this volume focuses on the planktonic forms of the open sea around Britain. What's wonderful about it is the enthusiasm with which it is written, the obvious excitement and wonder of discovery (the electron microscope had just been invented, deep-sea research was hardly routine), and the quaintness of the technical methods in the pre-electronic age. Where we can today drop down a temperature probe and have a second-by-second readout of the temperature at different depths of water, oceanographers of the past used an ingenious device called the reversing thermometer:

"The mercury tube of the thermometer, just above the bulb, has a loop and a kink in it, so that when it is swung rapidly upside-down the thread of mercury breaks; as soon as this happens all the mercury that before was above the kink now runs to the opposite, and now lower, end of the tube. When this is brought up the height of this inverted column of mercury is seen against a scale which can only be read when the thermometer is upside down; it tells us the temperature that the thermometer was recording at the moment it was turned over."

This was also soon after the invention of the Thermos flask and refrigerator, the latter quite a luxury in post-war austerity Britain. The next quote, on what the amateur should do after collecting a net-full of plankton from a tow, is instructive of both the social relations of the day, and who Hardy thought the typical reader for his book might be:

"... the samples which you should now have safely in your Thermos flasks to take home -- just be quite sure once again that you haven't put too much into them! It is well to take a quantity of extra sea water home with you so that you can dilute the samples still further before you put them into glass jars in the refrigerator. Two 7 lb sweet-jars are very good for this purpose; they can be conveniently carried in an oblong basket with a space just big enough to take one jar on either side of the handle and with a partition to keep them apart. When you reach home divide your samples out into as many large sweet or preserving jars as your wife -- or your neighbour!-- will allow you to keep in the refrigerator."