122 PROCEEDINGS OF THE SOUIE'IT. 



Mr. Shillington Scales then gave a lecture on " Photomicrography 

 of the Electrical Reactions of the Heart." 



In his preliminary remarks Mr. Shillington Scales said that he thought 

 perhaps he owed the Society an apology for lecturing on such a subject, 

 since it was somewhat beyond the province of the Royal Microscopical 

 Society. He hoped, however, that the Society would be interested in 

 seeing some work which had been done with perhaps the most recent 

 apparatus of the kind, namely the Einthoven String Galvanometer, which 

 was an entirely new method of dealing with the reactions of the heart. 

 His lecture would deal with both photomicrography and microscopy, 

 though he was bound to own that these sul)jects occupied a somewhat 

 subordinate position. Had he been speaking to an assembly of doctors 

 his task would have been easier from the medical side, or if to physiolo- 

 gists theii it would have been so from the physiological side, the same 

 applying to a society of electricians; he had, however, tried to bring 

 forward such points as he thought might prove not entirely without 

 interest to members of the Royal Microscopical Society, and he trusted 

 his subject would not be considered too technical. 



The extreme sensitiveness of the galvanometer, its cost, and its many 

 delicate adjustments, would prevent the instrument being used by other 

 than trained workers, but it had a distinct value as an addition— the 

 most recent — to our present methods of examination of the heart. The 

 principle of the method was based on tlie fact that every muscular con- 

 traction gave rise to a minute variation in potential, and the extraordinary 

 sensitiveness of the Einthoven String Galvanometer enabled it to make 

 these evident, so that they could be recorded. The galvanometer was 

 really one of the "moving coil " type, in which the " coil" was merely a 

 quartz fibre, 2 or 3 /x in diameter, silvered to render it a conductor of 

 electricity. This wire was suspended between the poles of an electro- 

 magnet and moved at right angles to them. The poles were bored to 

 admit the optical arrangement of a j\Iicroscope, consisting of a condenser 

 on one side and an objective and projection ocular on the other. Both 

 objective and condenser were focused on the quartz fibre. An arc lamp 

 was used as illumination, and the image of the fibre was thrown on a 

 cylindrical lens, thus forming a moving spot upon a long travelling 

 photographic plate, enclosed in a suitable box and with ingenious 

 mechanism for the necessary movements. The electrodes were merely 

 moistened plates of aluminium, and were not applied to the heart, but 

 merely to the bands and feet. 



To facilitate comparison of results with other workers, three main 

 leads were agreed upon, from the right hand to the left hand, from the 

 right hand to the left foot, and from the left hand to the left foot, and 

 the result of the tracings from these three leads would show consider- 

 able and important divergences. It had also been agreed to accept as 

 {I standard of sensitivity a movement of the galvanometer such that a 

 difference of potential of one millivolt gave a movement of the fibre on 

 the screen (at a standard distance) of one centimetre. It was not 

 necessary that the patient should be immediately near the instrument : 

 delicate as were the currents they could be recorded at a considerable 

 distance, and wires had been laid on from the room in which Mr. 



