4 THE ROYAL SOCIETY OF CANADA 
medical men of to-day are becoming specialists in remote branches of 
knowledge may not be generally realized. It has struck me that I 
might serviceably bring these matters to your notice. 
The use of the older medical instruments has become so much the 
property of the most ordinary practitioner that we are apt to forget that 
these are instruments of precision, affording exact results and making 
medicine scientific. Even the crudest of them, the use of the finger 
in percussion by Auenbrugger and of the stethoscope by Laennec, 
opened up new worlds in the diagnosis and sure recognition of respira- 
tory disease. Their employment was based upon a knowledge and 
study of the principles of acoustics by medical men. We are apt to 
regard Helmholtz as a great physicist, and to forget that the great de- 
monstrator of the conservation of energy (and inventor of the opthal- 
moscope) was first a medical student, next an assistant surgeon in 
the regiment of Red Hussars, next a lecturer in Anatomy in Berlin and 
then Professor of Physiology in Kônigsberg. It was through physiology 
that Helmholtz approached physics. And on our part, now that 
opthalmoscope, stethoscope and microscope are every-day instruments, 
we are apt to forget what each has meant for the advance of Medical 
science. In the hands of medical users each has undergone successive 
improvements and new applications, until the stethoscope has given 
place to the phonendoscope, with magnification of the sounds produced 
by the different organs in action: the employment of electric light 
renders modern opthalmoscopy almost child’s play, so clear and ex- 
quisite are the pictures afforded of the interior of the eye: the principles 
of the laryngoscope have been so applied and expanded that with 
bronchoscope, gastroscope, cystoscope and other special instruments 
we can investigate the air passages, œsophagus, stomach, bladder and 
many other ducts and cavities of the body and thereby discover 
the actual sites of disease when previously we could but infer their 
existence. I will not pretend that the pre-instrumental period did not 
develop physicians of singularly acute observation; I firmly believe 
that the older generations excelled the physicians of to-day in tactile, 
visual and auditory finesse, and in mental grasp and power of reasoning. 
Admitting this, it must also be admitted that a single phenomenon, 
accurately seen and recorded, means an exact observation, means a 
positive datum in place of a possibly erroneous deduction. 
But it is to some of the more recent specialisations in medical 
science that I would more particularly draw your attention. 
There is no hospital of the first class nowadays but has its X-ray 
department, presided over by an expert; we have journals devoted to 
medical radiography full of discussions upon the minutiz of measuring 
the intensity of Réntgen rays, of tests of the value of the different 
