THE lecture on 'The Practical Side of Fine Temperature Control" delivered by L. T. Townson and R. Barrington Brock to the Society of Chemical Industry in May of last year is now available in pamphlet form as No. 11 of the review Service to Science issued gratis by Messrs. Townson and Mercer, Ltd., of 390, Sydenham Road, Croydon. The lecture dealt with constant-temperature baths, particularly for medium temperatures, and concentrated attention mainly on water baths, which the authors point out are superior to air baths both because of the low heat capacity of air and also, they say, because its low density gives it little inertia, and enables vortices, with consequent temperature differences, to form more easily. The first matter which the authors stress, and on which they give experimental evidence, is the importance of stirring. They believe that paddle stirrers are not sufficiently effective, and that the whole of the liquid must be caused to flow through the bath; this involves the use of a second chamber of some sort, either entirely separate, or formed within the bath by means of false sides or some similar device. Other points which are discussed in the lecture are the effect of thermostat lag, the advantages and disadvantages of proportional control and the effect of heat losses. It is apparently not always realized that these lead to permanent differences of temperature in the bath. In this connexion, lagging is discussed, and the advantages of reflecting metal sheets as insulation are pointed out.