But perhaps the most interesting observations and experiments were those made to determine the origin of the ‘dewdrops’ on grass and vegetables. In the first place, it is found that these drops do not appear on all plants. Some are wet, while others growing alongside are dry, though there could be no great difference in their radiating power. Then the leaves do not get wet all over, but only at the edges and on the tips. A closer observation reveals the fact that these so-called ‘dewdrops’ are formed at the end of the minute veins of the leaves and grass, and are not now recognised as dew at all, but moisture exuded from the interior of the plants themselves. Moreover, these drops always appear before the true dew in the evening, and very often are seen when no true dew is formed. They even appear when the vegetables are placed under conditions where condensation of the surrounding water-vapour is impossible, and must, therefore, be due to the vital activity of the plants. Another observation may be mentioned which clearly shows that moisture rising from below may become condensed on the cooled surfaces of loose material. If the weather is at all cold, the beard and moustaches get covered with moisture; and in very cold climates, the eyebrows, hair, and whiskers get covered with a coating of hoar-frost. The moisture which forms this certainly comes from the body, which is always at a much higher temperature than the surrounding air. All these observations and experiments have led to the conclusion that moisture is constantly being given off from the earth; and that, except on the rare occasions when a warm moisture-laden wind blows gently over a previously cooled surface, it only returns to the surface of the ground after being condensed into rain, sleet, snow, or hail. Dew is only a portion of the outward current trapped on the exposed and cooled surfaces of the grass and other bodies. COMRIE EARTHQUAKES. Regarding earth-tremors or earthquakes, which, curiously enough, seem to be mainly confined in Scotland to Comrie, in Perthshire, a correspondent writing from Comrie kindly favours us with the following notes as to the erection which is there devoted to the registering of earthquakes. Our correspondent says: I recently visited the building with a view of giving you a few notes as to its history and construction. I may state that about fourteen years ago, the British Association applied to Mr Drummond of Drumearn for leave to erect a house on his property, which he at once granted free of charge, and assisted to defray the cost of erection.