Lawn Mowers; Incubators

245. Operation and Care of Lawn Mowers. The wheels of the lawn mower permit it both to move easily over the ground and turn the knives which cut the grass (Fig. 139).

This means that they must be kept well oiled to work easily—that the shaft of the wheel must not become wrapped with grass, weeds, string or wire. Most machines are made adjustable, and the knives are set to allow them to pass close enough to the plate at the bottom of the mower to clip the grass as if the machine were a pair of scissors. Keep the knives properly adjusted in relation to this plate. Do not let them come so close that they touch the plate but very lightly, nor be so uneven that one end cuts grass, while the other misses the plate so far that it will not cut.

If the knives are kept properly adjusted and the mower is not abused by trying to cut wires, stones, or by being stored where it becomes rusty, it will seldom need sharpening.

Keep all bolts tight.

246. Storing Mowers. When storing for the winter, grease the knives with a heavy coat of unsalted lard, or cover them with some other protective material.

247. Scissors and Shears. In popular language, there is no distinction made between scissors and shears. Technically defined, scissors are less than six inches in length. Any similar cutting device of greater length is called shears. Both are devices used for cutting cloth, paper, pruning trees, and many other purposes. They consist of two knives riveted together at some point between the handle and the point of the blade. The two blades are so adjusted that as the open scissors are closed, they touch lightly as they pass each other until the tip is reached. When the scissors are closed, the blades should touch only at rivet and tip. Scissors not so adjusted will not cut well, even the the blades are very sharp. Dropping scissors often bends the blades. Blades may be straightened as well as sharpened, and thus make good metal scissors like new.

248. Principles Upon Which Incubator Works. A device for hatching chickens is called an incubator. In order to hatch chickens, the incubator must keep an average temperature of 102-1/2 degrees Fahrenheit. The thermometer should be placed in the center of the tray and on a level with the top of the eggs. The temperature of 102-1/2 degrees Fahrenheit must not vary greatly during the incubation of eggs.

The incubator must also permit of suitable ventilation and control of the moisture in the eggs.

There are incubators heated with hot water and others with hot air. The air or water in those commonly used in homes is heated with a kerosene lamp.

The device consists of a heating unit, a regulator or thermostat which, acting upon a valve or damper, regulates the admission of heat into the insulated box containing the trays of eggs, ventilators and a thermometer (Fig. 140).

249. The Body of the Incubator. The box-like body of a good incubator is set on strong legs which raise it to a convenient height. The trays slide into the box on cleats about two or three inches from the bottom of the body. They fit so that a slit about two inches wide is left between for the chickens to drop down under the tray as they hatch. Usually this is near the door. If the door is furnished with a glass to admit light, the chickens are attracted toward light and fall thru the slit.

The walls of the incubator are usually double so that air can be let in without making a draft. Dampers in the side of the machine regulate the admission of air. Ventilation both regulates the amount of air circulating in the incubator and the amount of moisture. Air from a damp room keeps the eggs moist. Air from a dry room dries them.

250. Incubators Heated by a Lamp. Choose a lamp which holds enough oil to last for twenty-four hours. Good lamps are usually made of metal and as plain as possible (Fig. 141).

The burner furnished with them is an ordinary lamp burner carrying a straight, flat wick. Metal chimneys are used, there being enough mica in one side to permit the flame to be seen. The chimney extends into a metal chamber containing the hot-water pipes, or into a chamber thru which air is taken and heated by the chimney. The fumes from the burning oil pass out into the room and not into the incubator. The heated air passes thru ducts into the incubator. These are often constructed of wood.

251. The Wick. The wick most generally found practical is the cotton wick, such as is used in ordinary lamps. It should be kept clean and renewed often. The lamp should be kept filled regularly. The wick must always be kept trimmed even, to prevent smoking.

Incubators heated by electricity have the heating unit placed either above or below the trays of eggs. The current is controlled by a thermostat.

252. Thermostat. The thermostat also raises the damper over the top of the lamp and air heater (Fig. 142), when the incubator reaches the temperature for which it is set, and lowers it when the temperature falls. When the damper is lifted, the heated air passes out into the room and not into the incubator. As soon as the incubator cools below this temperature, the thermostat contracts, letting the damper drop in place to retain the heat and direct it into the incubator. The thermostat works the same when a gas flame is used instead of a lamp. In electrical machines, the thermostat operates the switch, admitting much, little or no current, as is needed to maintain 102½ degrees Fahrenheit.

253. The Thermometer. A thermometer is placed in the incubator to guide the operator in regulating the temperature. It guides him in adjusting the thermostat and the heating device; that is, it shows him when to turn the wick of the lamp up or down.

Lamps should never be turned high enough to smoke. Smoke and gas in the room are likely to get into the incubator and harm the growing chicks.

254. Operation of Incubator. Set the incubator level; it is constructed to work on the level. Heated air rises—if the incubator is not level, the highest point will get most of the heat. It should be set in a dry room or dry cellar, which is well ventilated and well lighted. There should be no artificial heat in the room which is not regular. An uneven temperature gives difficulty in managing the heating of the incubator. The room should be free from dust.

Adjust the incubator and run it for two or three days to see that it is operating at a constant temperature before putting in the eggs.

Use only the best grade of oil, and use the same kind of oil all thru one hatch. Change in oil may necessitate a change in regulators which is not safe while the eggs are in the incubators.

Start the incubator with a good, clear, high flame in the lamp, so that it can be turned lower as the germs in the eggs begin to grow and generate heat.

Start the incubator at 100 degrees Fahrenheit, and by the second day, it will reach the temperature of 102 degrees.

Violent fluctuations of temperature in the incubator are dangerous and should be avoided.

Accuracy in reading temperatures and in adjusting the thermostat and ventilators is essential. Fill the lamp and turn the eggs regularly. Cleanliness is important. Disinfect the incubator between hatches, and air it well. Cresol soap and water make a good disinfectant for incubators. Turn and handle eggs with clean hands.

To know whether the incubator has the proper amount of moisture supplied, weigh the trays before filling, weigh after filling. At the end of the fifth day, weigh tray and eggs again, subtract the tray weight, which is constant, from the weight of the whole, and note the difference between this weight and the original weight of the eggs. If 100 eggs have lost 8.38 ounces, or 4.17 per cent of their weight, the moisture is correct.

If they have lost too much weight, give more moisture or less ventilation, but, remember, that pure air is essential to incubators, so do not shut off ventilation entirely.

If not enough weight is lost, open the ventilators, and, if necessary, for the next hatch, place the incubator in a drier place.

255. Egg Tester. An egg tester is a device for looking thru eggs to ascertain whether or not they are good. It consists of some device to keep all bright light away from the eyes except a few bright rays shining thru the egg. The hole should be about an inch long and three-fourths of an inch wide. A metal chimney with one such opening in the side used in a darkened room serves as an egg tester. A large piece of cardboard tacked over a sunny basement window is sometimes used, the hole being cut in the cardboard (Fig. 143).

Hold the egg between the finger and thumb before the opening. Look at the egg as the light shines thru it. Fig. 144 shows how good and bad eggs look when viewed in egg tester.