EXPERIMENTS WITH LIVING HUMAN BEINGS. 611 



nomena we have been watching with our spectroscopes for the last ten 

 years can not be explained on the existing- hypothesis, and that they 

 are simply and sufficiently accounted for by supposing that primordial 

 atoms are associated in the corona and dissociated in the reversing 

 layer. 



In this way the vertical currents in the solar atmosphere, both as- 

 cending and descending, the intense absorption in sun-spots, their asso- 

 ciation with the faculae, and the ajyparently continuous spectrum of the 

 corona, and its structure, find an easy solution. 



We are yet as far as ever from a demonstration of the cause of the 

 variation in the temperature of the sun ; but the excess of so-called cal- 

 cium with minimum sun-spots, and excess of so-called hydrogen with 

 maximum sun-spots, follow naturally from the hypothesis, and aiFord in- 

 dications that the temperature of the hottest region in the sun closely 

 approximates to that of the reversing layer in stars of the type of Sirius 

 and a Lyra. 



-**^- 



EXPEKIME^^TS WITH LIVING HUMAN BEINGS. 



By GEOEGE M. BEAED, M. D. 



MR. JOHN STUART MILL, in the preface to his work on « Logic 

 and the Principles of Evidence," observes that while in the 

 search for truth we may be able, in some cases, to avoid errors in- 

 stinctively and successfully, although unable to formulate the method 

 by which we do so, yet it is an advantage not to be dispensed with 

 to have a rational understanding of the philosophy of reasoning, so that 

 we shall not be forced to depend alone on blind and irregular instinct. 



In experimenting with living human beings there are six sources of 

 errors which instinctively physiologists and physicians sometimes guard 

 against and allow for, but which ought to be and can be, as I contend, 

 and shall here aim to prove, reduced to a positive science. As these 

 elements of error come in the main from the nervous system, their 

 study belongs preeminently to neurology, or the study of the nervous 

 system in health and disease ; and it is because of the backwardness 

 of this specialty that the subject has been thus far passed by. 



The deficiencies of our knowledge of this subject were forced on 



' An abstract of a portion of this paper was read before the American Neurological 

 Association at New York, June, 1878. This essay relates to questions suggested in my 

 series of papers on "The Scientific Study of Human Testimony," published in the May, 

 June, and July (1878) numbers of the " Monthly," and may be of service to those who are 

 interested in that subject. This department of science is of especial interest at the pres- 

 ent time, when the experiments of Charcot and the criticisms upon them are exciting so 

 much attention. 



