SCIENCE SIFTING

New Zealand Tablet, 22 September 1921, Page 46

SCIENCE SIFTING

By "VOLT"

, ' THE BRAIN AT ITS BEST. At ivhat time of day is the mind of the. average man, doing an ordinary day’s work, most efficient? This question is asked and answered by London Tit-Bits thus: ' Suppose that he rises between seven and eight in the morning and goes to bed about eleven, when is he most fit for the execution of the problems of the day requiring the application of brain power ? The answer, according to recent investigations by an eminent psychologist, is “between 10 and 11 a.m.” * Tests were made on 165 persons, and the average of the results is set out in the following “efficiency table” covering the working day from 8 a.m. until 5 p.m.: —, Hour 8, efficiency 100; 9, 104.3; 10, 106.6; 11, 105.6; 1, 98.7; 2, 100.6; 3, 105.1; 4, 104.2; 5, 100.4. , It will be seen that the midday meal — between twelve and one o’clock —is followed by a striking drop in efficiency, and it is suggested that the meal should not be followed immediately by a resumption of work, but by an hour devoted to rest or recreation. The mind would then come back to work with increased efficiency. Navvies, haymakers, and other hard workers have from time immemorial recognised the need of a rest at midday, and many eminent brain-workers have followed their example. In city offices the man who went to sleep for half an hour after lunch would probably be regarded as a slacker, but a siesta might enable the office worker to do more and better work during the afternoon. Next to a nap, the best thing is said to be a game of some sort. A LAKE WHICH GROWS WHEAT. Not far from Adelberg,‘in Mid-Eastern Europe, where many mysteries of the underground world are hidden in the caverns among the chalk hills, there lies the lake of Cirknitz. It is some four square miles in size, with little islets studding its waters, into which run several” small streams. From this lake the villagers on its shores obtain not only fish and water-fowl,, in which it abounds, but also heavy annual crops of wheat and vegetables (says Everyday Science ). In early spring, after there have been some weeks of rain, Lake Cirknitz increases much in depth and size, whether the rains are local or not. As summer comes, and drier weather with it, the waters begin to disappear, taking with them, so the villagers aver, the fish and waterfowl. When this happens the people watch attentively. As soon as a certain islet shows high and dry they make a rush for the shore to catch as many fish as possible, for at this stage Cirknitz hastens its departure. In a few hours the last of its waters are gone, and the bottom lies bare. There are then disclosed to view great crevices and fissures in the bed of the lake. These openings as yet have not been, bottomed by the sounding line. The bed of : the lake soon becomes dry enough for the people to work on the muddy portions which overlie the upper stratum of rock. Before the summer is finished they cut grass where they have fished, and sow and ' harvest wheat and other cereals, and raise much produce, where in winter and early spring the r water stood many feet deep. ' , ’. ; Science explains it all by the statement that the lake must be connected underground with other bodies .of water, some higher in the mountain ranges nearby, and some lower ’ than itself. The villagers look upon it as a miracle annually performed for their own special benefit;