ment is made by dropping a specified coin in the slot. It is the practice of central stations to install "primary meters" on their switchboards to measure the total energy that goes out, thereby providing a perfect check on the aggregate amounts delivered to their customers. Some meters capable of measuring up to 25,000 horse-power in electrical energy, are made for this purpose. Electric railway companies employ meters on their cars as a check on the efficiency of the motormen. No system of inspection can equal the infallible and convincing record of the car meter in revealing careless use of controller or brake, often amounting to a loss of 20 per cent. The "two-rate" meter has been designed to encourage the use of electricity by automatically throwing resistance into the meter circuit whereby the meter is made The "arc" meter measures the current flowing from the central station to supply arc lamps. The "polyphase" meter has been developed in response to a demand for a meter that could render an accurate record of single-, two-, or threephase electrical energy upon a single dial. CALIBRATING. The expert compares the readings of the instruments on the bench and panel, with the running of the meters, one of which is shown at the right. The current passing through meters and instruments is controlled by the panel switches. to run more slowly for current consumed between certain hours of the day during which the central station is ordinarily under light load. This is accomplished by the use of an apparatus mechanically separate from but electrically connected to the meter, and comprising a clock mechanism and batteries. Wherever electric power is used and paid for, an electric meter is required; and in recent years the enormous growth of the use of electricity has resulted in phenomenal increase in the demand for these instruments, which have been found to be indispensable requisites of commercial success. Machines for Rearing Prematurely Born Babies are of Ingenious Construction and Save Many Lives I By RUTLEDGE RUTHERFORD NFANT incubators, or machines for saving the lives of prematurely born babies, deserve a place in the first rank of the great inventions of the day. They originated in France, and are the product of a peculiar state of affairs in that country, which for a time seemed threatened with "race suicide" because of the great mortality from premature births. Although the incubator is constructed of glass and metal, and permits of a good view of the infant inside, the conditions in the interior of the machine as regards temperature, humidity, air, etc., are made as nearly as possible like those of the child's ante-natal environment. premature While the machines have been employed for several years in France and Germany, they have only recently entered conspicuously into American life. They have been shown at fairs and special exhibitions; and a display of them at the White City, Chicago's great new amusement resort, has proved one of the most attractive features of the big show. Here may be seen from six to a dozen of the tiny scraps of humanity reposing in their little nests unmindful of the gazes of the curious crowds without. This strange exhibition is in charge of Dr. Martin A. Couney, a scientist who introduced the machines into Germany, England, and America. He watches over the infant brood with the care of a real parent, and performs the office of a foster father to the little ones born of mechanical mothers. Science has long since discovered that the only way of saving prematurely born children is to protect them absolutely from change of temperature and from cold. For such purposes, children used to be wrapped in wadding or in sheeps' skins with the wool adhering. The peas(68) ants of Silesia and Westphalia sometimes placed infants in a jar full of feathers. In England, the cot or cradle was put close to the hearth, and it was necessary to watch the fire day and night so that the temperature might not vary. The use ding of the cot is also a very general of hot-water bottles inserted in the bedpractice in this country and Europe, and and other hospitals. But such devices this method is adopted in many maternity are not uniformly reliable; their success depends upon the intelligence and assiduous care of the attendant; and the accidental opening of doors or windows, an unexpected or sudden gale, or a fall of temperature, may defeat the effect of even the most elaborate precautions. Some sixty years ago, Dr. Crédé, of the University of Leipzig, sought to effect an improvement on these primitive. and unreliable methods. He constructed a sort of box with double metallic sides; the space between these walls could be filled with hot water so as to maintain the desired temperature within the box. The in a basket or cradle, was placed inside. infant, covered with blankets and resting Incubators of this description are still lin. employed in the Charity Hospital, Ber ing the artificial couveuses (as incubators In 1878, Doctor Tarnier-when visitare called in Europe) installed by M. Odile Martin at the Jardin d'Acclimatation for the rearing of poultry-thought that he might utilize a similar apparatus in the case of prematurely born infants. M. Martin was therefore requested to construct a couveuse sufficiently ventilated and large enough to hold one or two infants. This was done, and the first Maternity Hospital in 1880. They concouveuses were introduced at the Paris stituted a noteworthy step forward in |