STRENGTH OF THE HUMAN JAW.

Taranaki Daily News, Volume L, Issue 61, 7 November 1907, Page 4

STRENGTH OF THE HUMAN JAW.

Tho crushing power of the hrman jaw ia surprising, varying from 150 to 300 founds. It is also surprising how much jaw strength is exerted unnecessarily by many persons in eating, oft-sn With the result of cracking or breaking the teeth They crush their food with the ferocity of wild animals.

Some experiments lecently made by 1> Joseph Head, of Philadelphia, furnish exact figures on this subject, which are as -aluable as they are interesting Weights are giver, for a large list of finds, and a comparison of the figur, 5 should be a \aaial>le buide in selecting the diet of tJusu who juv weak for any reason and need to economise thidr strength, also of those who chew with "stere Utth."

The first experiment was mads with dry crusts, which broke under 15 pounds pressure When, however, the combined crust and soft inside wcto tried, even 60 pounds pressure would not go through the dense mass. When a little saliva was added a pressure of three pounds was amply sufficient. The deductions with regard to fresh bread and tlnorough mastication are oh. vious. People ore sometimes greitly surprised at having broken a tooth when they "only bit a soft crust." Hero are a few figures taken from I)r Head's tables Of course, allowance js to be made for the fact that esuch food. and especially each kind of n.eat, will vary in reductibility according to quality and other oondif ions.

The weight needed to reduce corned beef, with the help of a little grinding movement, wa\ 20 pounds; for roast beef, 20 to 35 pounds; tough "round" sirloin 10 to 43 pounds; pork chops, 25 to 39 pounds. Tho lowest on the Est- was boiled beef, trrao pounds; roast lamb, four pounds; tonguc : one-half pound. Ko mention is made of hash.

Dr Black states the human jaw will ex ort a pressure as high eveo as 300 pounds. —Popular Mechanics.