ig: 



SCIENCE. 



[Vol. XVI. No. 400 



method employed by MM. Grancher and St. Martin was the injec- 

 tion of tuberculosis cultures attenuated in various degrees, and 

 used like the dried spinal marrow in Pasteur's treatment of rabies 

 and hydrophobia. Nine degrees of attenuation have been ob- 

 tained, the four last being such that the cultivation remained 

 sterile. The injections were made first with the most attenuated 

 cultivations, and then with more and more virulent ones. The 

 authors consider that by this method they have succeeded, on the 

 •one hand, in conferring on rabbits prolonged resisting power 

 against the most certain and the most rapid experimental tuber- 

 culosis, and, on the other hand in conferring an immunity against 

 that disease, the duration of which remains to be determined. 



A Return to Blood-Letting. 



M. Crocq, who has frequently written and spoken. in favor of 

 the revival of venesection, made a powerful speech dealing with 

 this subject at a recent meeting of the Belgian Academie de 

 Medecine, says the Lancet of Aug. 9. Speaking of pneumonia, 

 he declared his disbelief in the cause of the disease being either 

 Friedlander's bacillus or the diplococcus of Fraenkel and Weich- 

 selbaum. Inoculation of this latter microbe, he remarked, is said 

 to procure immunity from subsequent inoculations, which is ex- 

 actly contrary to the effect of an attack of pneumonia, for it 

 rather predisposes the subject to subsequent attacks. Again, M. 

 Crocq injected sputum from pneumonic patients in which the 

 ■diplococcus had been found, into the lungs of four rabbits, but 

 none of them contracted pneumonia. Lastly, in a doubtful hos- 

 pital case the sputum was examined, and found to contain the 

 diplococcus, but at the post-mortem examination no pneumonia 

 was discovered. M. Crocq has never met with any cases of con- 

 tagion in pneumonia, and Finckler's cases he considers were not 

 pneumonia at all. Moreover, Fraenkel's microbe is found in 

 affections which are neither pneumonia nor contagious. The 

 mortality usually reported by other observers in pneumonia varies 

 greatly ; that is to say, from 5 to 35 per cent. M. Crocq has no 

 mortality at all. He arrests all his pneumonia cases by bleeding. 

 Rheumatic- fever, and even puerperal metro-peritonitis, he treats 

 in the same way. The latter, he declared (amidst tokens of dis- 

 sent) can be thus cured in the great majority of cases. " Never," 

 he went on, " have I regretted havingbled a patient, though I have 

 often been sorry that I have abstained from doing so. ... If I 

 were to be forbidden to bleed, I would give up the practice of 

 medicine." He was, of course, careful to explain that blood-letting, 

 to be of any service, must be practised intelligently, and not 

 abused, as he fears it may again come to be after the wave of re- 

 action has once more made it popular. 



LETTERS TO THE EDITOR. 



*♦* Correspondents are requested to be as brief as possible. The writer's name 

 is in all cases required as proof of good faith. 



The editor will be glad to publish any queries consonant with the character 

 of the journal. 



On request^ twenty copies of the number containing his communication wili 

 i}e furnished free to any correspondent. 



Professor Hazen and Espy's Experiments. 



A CORRESPONDENT has recently called my attention to certain 

 communications of Professor Hazen to Science and the American 

 Meteorological Journal, in which Espy's experiments are assailed, 

 and thus indirectly my theory of cyclones and tornadoes, and he 

 thinks there should be a reply to them. A reply, so far as they 

 bear upon my theory, if thought necessary, is very easy; so easy, 

 indeed, that I had not thought it necessary. Besides, I have been 

 desirous of avoiding an unprofitable controversy with Professor 

 Hazen on this subject. 



Inasmuch as I have never used any of the results of Espy's 

 experiments, any attack upon these experiments does not reach 

 me, except so far as it may bear ui^on the results of other great 

 physical experimenters. It is true, I sometimes refer to this noted 

 pioneer in meteorological advancement, as any one in this age 

 may still refer to Kepler and Newton, and very properly, but it is 

 not at all necessary. The formula which I have used throughout 

 in my researches, as the basis of the physical part of my theory. 



and which completely covers the ground of Espy's experiments, 

 is one given by Dr. Hann in a paper published in the Zeitschrift 

 of the Austrian Meteorological Society for 1874, and translated by 

 Professor Abbe, and republished in the " Smithsonian Report for 

 1877." This formula, in a somewhat different form, originated 

 with Sir William Thomson, and has been used, and gradually 

 brought to its present form, by Dr. Reye, Peslin, Clausius, Hann, 

 etc., and so rests upon high authority. The physical constants 

 in this formula have been determined by renowned experiment- 

 ing physicists. They are the mechanical equivalent of a unit of 

 heat, the specific heat of air, the latent heat of aqueous vapor, the 

 tension of the aqueous vapor of saturated air at any given tem- 

 perature, etc. From this formula liave been computed the rate 

 with which ascending dry air decreases in temperature with in- 

 crease of altitude, which is 0.99° for each hundi-ed metres, and 

 also the same for ascending saturated air at given temperatures 

 and altitudes. These latter are given in Table III. of the appen- 

 dix of my '■ Popular Treatise on the Winds," etc., and range from 

 0.37" for a high temperature at the earth's surface, up to 0.74° for 

 a temperature of — 10° C, the values for all temperatm-es decreas- 

 ing with increase of altitude. With these data I have illustrated, 

 by means of the table on p. 233 of the work referred to above, 

 how the temperature in ascending currents decreases with increase 

 of altitude under different assumed conditions, and have shown 

 that it is very much greater than it would be in the case of dry 

 air, and also greater than that of the surrounding air when the 

 lower strata become a little more warmed up than usual in com- 

 parison with the upper strata. All these results have been de- 

 duced from a formula resting upon the high authorities already 

 mentioned, and having had its origin with Sir William Thomson 

 less than thirty years ago. Yet Professor Hazen makes the aston- 

 ishing assertion that nothing has been done since Espy's time, 

 more than fifty years ago, and that " the profoundest calculations 

 and speculations upon the development of energy in the free air 

 are based upon a few experiments of the crudest sort made in a 

 small jar." 



The latent heat of aqueous vapor in the formula referred to, as 

 determined by Regnault, may be expressed for ordinary tempera- 

 tures by ?'=607— 708f ; but according to Hazen it should be r=0, 

 for he maintains thalT there is no latent heat set free in condensa- 

 tion. With '/'=0 in the formula, instead of the numbers in the 

 table referred to above, ranging at the earth's surface from 0.37° 

 to 0.74°, and being still less at high altitudes, we should have for 

 all temperatures and altitudes 0.99°; that is, the rate of decrease 

 of temperature in all cases would be that of ascending dry au-, 

 and of course the energy upon which the cyclone or tornado 

 depends would be much diminished. Now, if Regnault has made 

 so great a blunder, and a cloud is thrown over his reputation by 

 Hazen's experiments, it is for the experimenting physicists of the 

 day to take up the matter, and not for me ; for I am not an ex- 

 perimenter, and, if I have erred, it is in relying upon insufficient 

 authority. 



It has never been claimed, even by Espy himself, that his ex- 

 periments were of a refined and accurate character, and that his 

 results were any more than rough approximations. They have 

 been regarded as important first steps only. Espy says, " I would 

 not wish to be understood here as saying by implication that the 

 numbers used in this paper are strictly correct. These numbers 

 are introduced chiefly for the pui-pose of illustrating the theory." 

 He again says with regard to his results, "The grand object, 

 then, for which these experiments were instituted, is established 

 beyond doubt, — that the latent caloric of vapor causes the air to 

 occupy much more space when it is imparted to the air than 

 when it is united with water in the form of vapor." The same is 

 shown by Dr. Hann's formula, but the latter gives quantitative 

 results. Espy inferred from his experiments that when dry air 

 ascends it becomes colder about 1.35° for every hundred yards of 

 ascent. The true amount is 1.6°. He also infen-ed, that, when 

 air ascends from the earth, it will begin to form cloud when it 

 rises about as many times one hundred yards as the temperature 

 of the air is above the dew-point m degrees of Fahrenheit. The 

 true number is seventy-six yards. 



There is a great error in several of Hazen's papers with regard 



