CHAPTER XV
GENERAL HYGIENE
"Better to hunt in fields for health unbought,
Than fee the doctor for a nauseous draught."
—Dryden.
If men but realized what complicated machines they were, they would use themselves better. In the body are 240 bones and hundreds of muscles. The heart, no bigger than the clenched fist, beats 100,000 times a day; the aerating surface of the lungs is equal in area to the floors of a six-roomed house, and by means of its minute blood-vessels which would stretch across the Atlantic, 500 gallons of blood are brought into contact with over 3,000 gallons of air every day.
Seven million sweat-glands, 30 miles long, get rid of a pint of liquid and an ounce of solid waste each day while it takes a tube 30 feet long, with millions of glands, to deal with a sip of milk.
Man's finest steam engine turns one-eighth of the energy supplied into work; nature's engine, muscle, turns one-third into work. The body contains 9 gallons of water, enough carbon to make 9,000 lead pencils, phosphorus for 8,000 boxes of matches, iron for 5 tacks, and salt enough to fill half a dozen salt-cellars.