XXVI.—Temperature Observations in Loch Earn. With a further Contribution to the Hydrodynamical Theory of the Temperature Seiche

Extract

There are a number of gaps which exist in our knowledge of the temperature changes which occur in fresh-water lakes. The broad lines on which the changes occur are fairly well known, but on almost every point there is a lack of detailed knowledge, and every investigation shows new problems requiring attack. One of the most interesting of these problems is the causation of the temperature seiche, and the effect of varying meteorological conditions. The problem is a difficult one, as the factors to be taken into consideration are so numerous, and the data from which to form conclusions are difficult to procure. We must first obtain an accurate knowledge of the changes which are occurring in the body of water under consideration—not only at one point but at all points, and this necessitates observations at frequent intervals of time, at numerous depths, made from several points on the surface of the loch. As yet there are no satisfactory self-recording instruments by means of which we can record the temperature of water at a considerable depth below the surface, and recourse must be had to the reading of mercury thermometers.