From New Scientist, November 29, 1956, page 21.
“…it will be necessary to measure their bodily energy exchanges; and this can be done with a modern apparatus called the IMP (integrating motor pneumotachograph). This consists of a light air pump and flowmeter housed in a plastic box, which connects on one side with a mask fitted over the face and on the other with a sample-collecting unit packed in a bag worn on the back. The IMP measures, over a given time, the total volume of air breathed out by its wearer, and from this expired air it automatically takes representative (or integrated) samples. The whole apparatus is so light, well-fitted and comfortable that it can be worn easily during violent exercise or peaceful sleep.
“The IMP was designed by Mr. H.S. Wolff, of the Human Physiology Division of the National Institute for Medical Research, to enable physiologists to study human energy exchanges under conditions ranging from swimming the Channel to bathing a baby. It has attachments allowing the wearer to drink through a tube or blow a whistle; though as yet the IMP cannot measure man’s energry exchanges while he is chatting, smoking, shaving or eating. It is manufactured by J. Langham Thompson.”