G Sims Woodhead, P.C Varrier-Jones
1916 The Lancet  
PART II.*—THE THERMO-COUPLE THERMOMETER. IT will be gathered from perusal of Part I. that the relation of temperature to disease has been studied and recorded so fully that an enormous mass of literature on the subject must have accumulated. Much of this literature is of a single type and has a common origin. From time to time, however, the need of improved methods and extended observations has been brought home with great force to those engaged in practical clinical thermometry. On the one
more » ... try. On the one hand the measurement of extremely slight variations of temperature was demanded, whilst on the other, as the diurnal variations of temperature were demonstrated, more frequent and repeated observations became necessary. These demands have been oft repeated, and clinicians and physicists alike have exerted great ingenuity and expended much of both time and energy on the construction and working of apparatus designed to obtain continuous records of slight variations of temperature, or such records at short intervals, over prolonged periods. Discussing Allbutt's work, an unnamed writer says 5s :— But as the local variations are sometimes slight, although occasionally amounting to 40, 50, 60 F., or even more, the ordinary thermometers ...... are not sufficiently delicate to detect them readily ; accordingly a thermo-electric pile capable of registering very minute variations has been constructed, and, from what we have seen, is likely to lead to highly important results. The real value of this thermo-electric apparatus (the possibility of obtaining continuous records of the temperature in different parts of the body) is, however, passed unnoticed. Even then it had come to be recognised, and now still more is it evident, that the stage had been reached at which the mercurial clinical thermometer, a proved instrument of precision of great value in advancing medical science, could no longer be considered equal to all the demands made upon it; some method of continuous registration and recording of temperatures is called for. The mercurial thermometer, in spite of its many good points, has certain imperfections. At best it registers the maximum temperature only, within the cavities in which it is placed. The most delicately constructed mercurial thermometer, after being placed in position, indicates the maximum temperature of the tissues of the body with which it is brought into contact only after a distinct interval; the " lag " of the instrument is considerable and, as usually constructed and graduated, this * Part I. was published in THE LANCET, Jan. 22nd, p. 173. No 4823 thermometer does not indicate very low temperatures, whilst outside the usual range inaccuracies are almost unavoidable. With such an instrument no graphic records of any variations of the body temperature can be obtained. It can supply no information as to the variations of temperature which occur, even while it remains in position, and during the intervals between its application we are, of course, completely in the dark as to what rise or fall of temperature may be taking place. We may take the patient's temperature every four hours, but we still remain in ignorance of the course of events during the intervening four-hourly periods, and may miss the indications of a distinct but moderate tuberculin reaction or of severe internal hmmorrhage, occurring, say, after an operation. GAMGEE'S WORK ON CONTINUOUS TEMPERATURE RECORDS. Arthur Gamgee,63 who during the last years of his life devoted all his energies to the production of continuous or quasi-continuous temperature records, writes :-The careful and detailed study of all the work done since the earlier observations of Jürgensen 64 and others on the diurnal variations of the temperature of man shows in the clearest possible manner that it can only be by the introduction of automatic and extraordinarily sensitive methods of registration that the wonderfully interesting problem of the diurnal variations in the animal temperature and their relation to mean tirne, as well as to the other conditions probably affecting it, could be attacked and solved. Gamgee was ultimately successful in his efforts to obtain continuous temperature records, and had his life been prolonged he would have done the work on which we are now engaged. He says :- The motive which urged me to make the sacrifices of all kinds which this research has involved was the intense desire to study for the first time, and in an elaborate manner, the normal curve of the temperature of man, and thereafter, in the first instance, the changes which that curve exhibits during the very earliest stages of pulmonary consumption and of surgical tuberculosis when the organism is the prey of the tubercle bacillus alone and not yet subject to a "mixed infection"; for I had, by long-continued observations carried out with the clinical thermometer, ascertained the utter want of precision and insight which at present prevails in reference to the very earliest stages of phthisis, when physical signs are yet almost, or completely, in abeyance, and when the cough, the anaemia, the loss of flesh, and slight temperature abnormalities are the only guides the physician has to rely upon. The conditions under which an automatic method of registering the differences in the E.M.F. of thermo-couples could be carried out had completely changed since the days when I worked with Tait. The discovery of the moving coil type of galvanometer, which we associate with the name of D'Arsonval, but which had been initiated by the beautiful syphon-recorder of Lord Kelvin, had, to. my mind, absolutely simplified the solution of the problem. Given a galvanometer practically uninfluenced by all changes in the surrounding magnetic field, and at the same time possessed of great delicacy under the conditions of the special investigation ; given, besides, an extremely perfect photographic recorder ; and, thirdly, given a thermostat more perfect than had ever been constructed, which should be able to maintain a thermo-couple during days and weeks at a temperature not varying more than 0'020 C. ; fourthly, given thermo-couples of sufficient delicacy, and of which one set should be so arranged as to constitute respectively very perfect surface and deep thermometers, and it appeared to me that the problem must be definitely solved. EARLY OBSERVATIONS WITH THE THERMO-ELECTRIC METHOD. Seebeck, in 1822, noted that a difference in electrical potential was produced by raising or lowering the temperature of the " junction" of two dissimilar F
doi:10.1016/s0140-6736(01)10905-0 fatcat:rxgibiq6gnfmzpoaajiwsn2pwe