One important and characteristic feature of the present age is the conservation of waste in perishable foodstuffs. Fruits, vegetables, fish and oysters were suitable food to our forefathers only when freshly taken, and any superabundance in supply was either wasted by natural processes of decay, or was fed to the hogs. To-day thousands of patented fruit dryers, cider mills, and preserving processes save this waste and carry over for valuable use through the unproductive winter months these wholesome and valuable articles of diet. Even more important is the _canning industry_, by which not only fruits are maintained in a practically fresh condition for an indefinite time, but oysters, meats, fish, soups, and vegetables are also put up in enormous quantities. To-day the grocer’s shelves present an endless array of canned tomatoes, peaches, corn, peas, beans, fish, oysters, condensed milk, and potted meats, which constitute probably three-fourths of his staple goods. The tin can is in itself a very insignificant thing, not entitled to rank with any of the great inventions, but in the every-day campaign of life it is playing its part, and working its influence to an extent that is little dreamed of by the casual observer. It renders possible our military and exploring expeditions; it holds famine and starvation in abeyance; it gives wholesome variety to the diet of both rich and poor; and it transfers the glut of the full season to the want of future days. Perhaps no single factor of modern life has so great an economic value. Simple as is the tin can, quite complex machines are required to make it. Originally such machines were operated by hand or foot power, but within the last 25 years power machines have been devised which automatically convert a simple blank or plate of sheet metal into a finished can. Of the many patents granted for such machines the most representative ones are 243,287, 250,096, 267,014, 384,825, 450,624, 465,018, 480,256, 495,426, 489,484. In the process of putting up canned goods the products are filled into the cans, and the caps, or heads, are soldered on. These caps have a minute hole in the center for the escape of air and steam in the process of cooking and sterilizing, which is conducted as follows: A large number of cans are placed on a tray swung from a crane and the cans lowered into one of a series of great cooking boilers. The cover of the boiler is then closed and fastened by lugs, and steam turned on until the goods in the can are thoroughly heated through. During this process the air and steam escape through the little vent hole from the interior of each can. The cans are then removed, the vent hole closed by a drop of solder, and the goods thus hermetically sealed in a cooked or sterilized condition will keep for a long period of time.