AuQ' 5, 1875] 



NATURE 



^1S 



invention, and giving the whole credit to Capt. Laussedat, 

 closing with the remark that if it should be successful the 

 glory would belong to France. Afterwards I received a 

 pamphlet of twenty-six pages, by Capt, Laussedat, in 

 which, ignoring me entirely, he tried to sustain his claims 

 against those of Faye, Foucault, and Fizeau. 



In 1873, after the horizontal telescope had been in 

 successful operation for three years, after specimens, both 

 negatives and lithographic copies had been distributed in 

 Europe, the French Commission, which had up to this 

 time been making their preparations to use the method 

 of de La Rue, adopted the horizontal telescope. It would 

 appear from this, that whatever might have been done or 

 said on this subject by the Frenchmen named above, it 

 had not contributed much to a clear appreciation of the 

 advantages of the method until after they had been de- 

 monstrated here. 



Without caring anything about credit for priority of 

 suggestion in such matters, being satisfied that no similar 

 instrument was in use or had been used before the one 

 at Harvard College, I was yet interested enough in the 

 matter to look up the claims put forth by these gentlemen, 

 and to see why they happened to be overlooked for so 

 long a time, even by their own countrymen. I find 

 that credit is accorded to Foucault, mainly for his per- 

 fection of the heliostat, both for the plane mirror and 

 for the uniform motion. He published nothing in re- 

 gard to its application to photography. After his death 

 his friend, St. Claire Deville, spoke of it as one of 

 the things that Foucault intended to do. He at the 

 same time contemplated the use of the siderostat in 

 £ll kinds of astronomical observations. M. Laussedat 

 is unwilling to give him any share of credit for the hori- 

 zontal telescope. M. Faye gives him credit only for the 

 heliostat. 



M. Faye himself took some photographs of the sun 

 with a very long telescope of one M. Porro, of 15 meters 

 focal length. The telescope was pointed directly at the 

 sun. M . Faye's remarks on them before the Academy 

 related only to the advantage of their size and their distinct- 

 ness. He had nothing to say about the peculiar advantages 

 of the long telescope, but he anticipated all succeeding 

 inventions in the application of Photography to astronomy 

 by predicting its early use in meridian and every other 

 class of observations. 



His next communication on this subject was on March 

 14, 1870, on the occasion of presenting a letter from M. 

 Laussedat on the subject' of a horizontal telescope. This 

 was six months after my apparatus was ordered, and after 

 some experiments had been made with it. In this 

 communication he appears at first glance to have 

 suggested the whole arrangement now adopted ; but 

 on closer examination he does not seem to have had any 

 clear ideas about it. He recommends the use of a long 

 telescope because he had seen good pictures with a long 

 telescope ; he nowhere speaks of his reasons for dispensing 

 with the eyepiece, and in fact it does not clearly appear 

 that he did dispense with it. In September, 1872, after 

 it had been in use for two years and several accounts 

 of it had been pubhshed, in his comments before the 

 Academy on a paper of Warren De la Rue's, he seems to 

 have understood for the first time the true theory of the 

 long horizontal telescope. 



Capt. Laussedat appears to have the most substantial 

 claim of any that have been mentioned thus far. He used 

 a horizontal telescope in Algeria in i860, in observing the 

 total eclipse of that year ; but he used a very short tele- 

 scope and had an eyepiece to enlarge and distort the 

 image. His own account of what led him to this method 

 was that he had no equatorial mounting for his little tele- 

 scope and that no means were furnished him to buy one, 

 but he had a good heliostat, and he resorted to the 

 method as a makeshift. He fully appreciated, however, 

 the advantages over the other method in the accuracy of 



orientation and in the certainty with which fixed lines of 

 reference could be had on the plates. 



M. Faye, in his communication of Sept. 1872, seriously 

 claims that his use of the long telescope pointed to the 

 sun in 1858 — because M. Porro happened to have one, 

 and Capt. Laussedat's use of a short one, placed horizon- 

 tal, because he had no equatorial stand and clock move- 

 ment—together make up the invention of the telescope as 

 it is now used. 



But, after all that has been said about the priority of 

 suggestion, that question is settled finally by some one * in 

 England finding that the wole arrangement was suggested 

 by Hooke in 1676. A late communication on the subject 

 in the New York Times calls it a method suggested by 

 Hooke and perfected by Foucault. 



In Hooke's day they had none but very long telescopes, 

 but they had no heliostats. No practical application of 

 his suggestion, however, seems to have been made. 



ON THE CARDIOGRAPH TRACE 



TD Y placing the sphyginograph, as constructed by M. 

 J-' Marey, over that portion of the chest where the heart 

 can be best felt beating, instead of on the wrist-pulse for 

 which the instrument is constructed, tracings called 

 cardiograms can be obtained which bring to light physio- 

 logical facts not otherwise ascertainable. In the last- 

 published volume of the Guy's Hospital Reports there is 

 a paper by Dr. Galabin, on the interpretation of these 

 tracings, which will be read with interest by physiologists 

 on account of the considerable difficulty there is con- 

 nected with all attempts to explain the numerous ups and 

 downs which they present between any two pulsations of 

 the heart, and also because of the comparatively slight 

 attention which they have had paid to them. 



Dr. Galabin, in the paper under consideration, limits 

 his observations almost entirely to the vertical variations 

 in the curves under consideration, paying but httle atten- 

 tion to the differences in the relative lengths of systole 

 and diastole which they so clearly indicate, and which 

 cannot be recognised with any degree of accuracy by any 

 other means at our disposal. From a study of the cardio- 

 graph trace, he is led to the conclusion that the two most 

 important elevations in the systolic portion of each curve 

 are produced by the muscular movements in the heart 

 itself, because " the more the heart is hypertrophied (by 

 disease) the more prominent in comparison do these two 

 become," and under these circumstances, "the effect of 

 any oscillations, either of the blood or of any solid struc- 

 tures, would become less noticeable in proportion." It is 

 remarked that " Marey's figures (of tracings indicating 

 intracardial pressures) prove that the first, at any rate, of 

 the cardiac impulse is not due to any stroke against the 

 ribs caused by locomotion of the heart as a whole, which 

 could only commence after the opening of the semilunar 

 valves," because " the aortic valves do not open until the 

 ventricular pressure has nearly reached its first maximum." 

 It must, however, be noted that other tracings, obtained 

 by the same illustrious physiologist, demonstrate equally 

 clearly that the maximum of intracardial pressure is 

 reached some appreciable time before the first major 

 systolic cardiograph rise in the trace from the chest-wall, 

 so that it may still be reasonably argued that the rise 

 referred to depends upon the locomotion of the heart en 

 masse. 



To explain the second main systolic rise. Dr. Galabin 

 makes a statement which needs considerably more de- 

 monstration before it can be considered to be proved. 

 He refers to " inverted tracings," by which are understood 

 curves in which all the rises in an ordinary tiace are 

 represented by depressions, in such a way that " to see 

 more clearly their correspondence with positive tracings 



* A correapondent in Nature.— Ed. 



