IN DENTAL OPERATIONS. 83 



Having been for more than thirty years engaged 

 in researches in magnetism, electricity, and elec- 

 tro-physiology, as well as in the application of 

 electricity as a therapeutic agent, I have been 

 enabled from time to time to avail myself of the 

 experience derived in the study of one branch of 

 the science, to increase the facilities for investi- 

 gating the other branches ; thus discoveries of 

 the relation of certain laws to each other in the 

 phenomena of electro-magnetism led to the im- 

 provement of the apparatus employed for electro- 

 physiology and therapeutics, as the requirements 

 for such increased appliances suggested them- 

 selves. 



About sixteen years ago, I introduced a new 

 mode of graduating the force of the shock, by 

 dividing the secondary coil into equal and known 

 portions, and I subsequently still further increased 

 the accuracy and delicacy of this graduation, by 

 introducing a contrivance for subdividing each of 

 these degrees of power again into quarters, so 

 that by this means I was enabled to obtain a 

 range of power over 50 or more equal and minute 

 degrees. I was honoured by the Royal Cornwall 

 Polytechnic Society with their silver medal for 

 this invention. At the same time, by carefiil 

 attention to the arrangement of different parts, 

 I succeeded in reducing the size of the exciting 

 battery so as to be able to include the whole of 

 the apparatus in a very small box, and my humble 



