INFANT INCUBATORS Tarnier's Incubator.—The first incubator designed for rearing children who are too weak to survive under normal conditions, or who are prematurely born, was that of Dr. Tarnier. It was con structed in 188o and was first used at the Paris Maternity Hospital. Its form is that of a rectangular box measuring 65 X 3o X so centimetres (fig. 7). It is divided into an upper and lower chamber; the former con tains the infant, while the latter serves as a heating chamber, and in reality is simply a modified water-tank. The partition (P) which divides the incubator into two cham bers does not extend the whole length of it, so that the upper and lower chambers are in communication with each other at one end of the apparatus. It is through this passage that the heated air from the lower chamber passes into the upper one containing the in fant. The narrow bottom chamber (C) serves to prevent loss of heat from the base of the water-bottles. The outside air is admit ted into the lower chamber at the opposite end, through an aperture (A), and passing over a series of bottles (B) containing warm water, becomes heated. The air is rendered adequately moist by means of a wetted sponge (S) which is placed at the entrance of the lower chamber into the upper. The warmed and moistened air is determined in its direction by the position of the outlet aperture (0), which is situated above and just behind the head of the infant. It contains a helix valve (H) and the rotation of this is an indication that the air is circulating within the incubator.
The child is kept under observation by means of a sliding glass door (G) situated in the upper or roof wall of the incubator. Im mediately beneath this, and attached to one of the side walls, is a thermometer (T) which records the temperature of the air in the infant-chamber. The temperature should be maintained at 31° to 32° C. The precise limit of temperature must of course be determined by the condition of the child; the smaller and weaker it is, the higher the temperature must be.
The warm water vessels contain three-quarters of a pint of water and four of them are sufficient to maintain the required tempera ture, provided that the external air does not fall below 16° C. The vessels are withdrawn and replaced through an entrance to the lower chamber, which can be opened or closed by a sliding door (D). The walls of the incubator, with the exception of the glass sliding door, are made of wood 25 millimetres thick. Child incubators heated by hot water bottles on the same lines as Tar nier's are still used but need constant attention and have been superseded by machines of the type to be described.