402 CURRENT TOPICS. [J. F. I.

Experiments on Gravitation. L. MAJORANA. (Counptes Rm- dus, Acad. des Sciences, vol. clxix, Nos. 15 and 17, IgIg.)- A lead sphere of mass 1274 g. suspended from the right arm of a balance was counterpoised by a similar sphere on the left arm. Both spheres are surrounded by walls of the same shape. The first sphere has its centre coincident with the centre of a cylinder with vertical axis which can be filled with mercury of mass 104 Kg. The liquid is kept from touching even the protecting wall about the lead sphere. A vacuum was maintained within the balance case and all thermal, electrical, magnetic, and electro- magnetic effects were eliminated. As the result of a lengthy series of experiments, conducted at night or on days of general strike, it was found that the lead suffered a loss of weight of 0.0009 mg. when it is surrounded by the mercury, that is, a loss of 7.10-lo of its weight. This is of interest, since hitherto it has been believed that the force of gravity acts through matter just as if it were a vacuum.

G. F.S.

American Diet Changing. (Weekly News Letter, U. S. De- partment of Agriculture, January 21, 1920, vol. vii, No. 25, p. S.)- Whether it is because of the increased cost of meat or because people’s tastes have changed, the fact remains that Americans are eating 8 per cent. less meat than they were twenty years a,go. This is disclosed in a recent dietary survey made by the United States Department of Agriculture.

In this survey 2000 dietary records, each covering a period of seven days, were collected from 1425 families and 575 institutions in 46 states. Sixteen nationalities and many occupations and in- comes were represented, as were dso both urban and rural localities.

From a summary of 500 of these family records it appears that last year the average cost of food per man per day was 46 cents, with an average return in food value of 3225 calories, 96 grammes protein, 118 grammes fat, and 405 grammes carbohydrate. These figures are in fairly close accord with the dietary standards ordi- narily used in discussing such problems of general nutrition.

A comparison of the foodstuffs purchased by the 5oo families with the amounts of the same food purchased by 400 families about twenty years ago shows that the amount of meat in the American diet has decreased about 8 per cent., and the amount of grain prod- ucts about II per cent. People are eating more milk, butter, and cheese than they were two decades ago, for the amount of dairy products consumed has increased about 6 per cent. Four per cent. more vegetables and 8 per cent. more fruit are being eaten now.

Some individual food habits undoubtedly need to be corrected, but, judging by these studies, it seems fair to conclude that the aver- ‘age diet seems to be adequate.

R.