THE RELATION OF THE PULSE TO THE RESPIRATION. — The proportion which the pulse bears to the respiration has been va riously stated by authors. Quetelet et', Parry Burdach, and the greater number of physio logists estimate it as 4 to 1; Joy as 4A- to 1; and Floyer as 5 to I.§ M. Valleix states it at 4 to 1 in infants. Little dependence, however, is to be placed upon any of these estimates, as they were made in ignorance of the very remarkable effect of posture on the respiration ; and as the respiration itself was probably counted for very short intervals of' time, and under the disturbing influence of a consciousness of the observation which was being made. Though the posture of the body, in which the pulse and respiration were counted, is not distinctly, stated by the authors who have put forward the foreg,oing estimates, it is most probable that it was the recumbent posture; for it is in that posture that the breathing is most easily counted ; and as it is possible, when the subject of the observation is lying down, to place the hand on the abdo men, still retaining the hold upon the wrist, and to count the breathing while he remains unconscious of the object of the observer, the true number of the respirations, as compared with that of the pulse, may be ascertained with tolerable accuracy. Eighteen such ob servations, made by the writer on as many healthy young men, gave as the average pro portion 3.72 to 1, and thirteen observations on as many more healthy and adult females, the proportion of 3.61 to 1. The extremes, in the observations on males, were 2.54 to 1, and 5'33 to 1 ; and in females, 3-10 to 1, and 4'33 to 1. In these observations the re spiration was counted, immediately after the pulse, for two consecutive minutes. Bryan Robinson, as the result of three observations on the same number of healthy males in the sitting posture, obtained numbers of the pulse and respiration, from which the calcu lated proportions are 3.82 to 1, 3.79 to 1, and 3.86 to 1. Quetelet*, from a series of 300 experiments on males of different ages, ob tained the following proportions :— As the respiration is greatly under the control of the will, to obtain the requisite ac curacy in observations of this nature it would be necessary to adopt some measures by which it might be counted for several minutes at least in succession, the subject of the ob servation being either unconscious of what is going on, or having his attention diverted from it. This object the *liter has accom
plished by converting the common pocket pedometer into an instrument for registering the respirations ; and by means of it, bas made several hundreds of observations during pe riods of half an hour each, the pulse being counted for one or two minutes before and after each registration of the respirations, and the average of the two or four minutes being taken to represent the frequency of the pulse during the whole period of the experiment. The greater number of the experiments were made in the sitting posture, with the back supported, the attention being diverted from the breathing by engaging in study.* The, following are the principal results obtained in this manner : —the average proportion from 238 experiments performed in the manner just described, the pulse var3ing from 44 to 85 beats, and the respiration from 151 to 201, was 3-17 to 1. The extreme proportions were 2'61 to 1, and 5 to 1.
The average proportions varied with the number of the pulse, as shown in the following table From other observations by the same author, it would appear that the proportion of the pulse to the respiration during sleep is lower than in the same persons awake, in consequence of the respiration being more affected during sleep than the pulse. Thus, in a girl from 3 to 4 years of age, the mean proportion of the pulse to the respiration was 3.40 to 1 awake, and 3'68 to 1 asleep; in a boy from 4 to 5 years old, 3.21 to 1 awake, and 3.50 to 1 asleep ; and in a female in her 27th year, 2.85 to 1 awake, and 3.19 to 1 asleep. The averages are deduced from " un assez grand nombre d'observations," and were probably made in the recumbent posture.