coadjutor, Mr. John Shaw, instituted experiments to assist him in determining their functions, more especially those of the fifth and that of the portio dura of the seventh pair. These experiments were happily imagined : without the fortunate circum- stance that in certain parts of the body, especially on the face, the nerves of sensation and motion are distinct throughout their whole course, the great discovery of Bell could never have been clearly established.
It was about this time, and when making the most important advances in obtaining positive and undeniable proofs of the truth of his doctrines, that we find him, under an impulse like that exhibited in 1807, addressing his brother in Edinburgh in a letter bearing date the 17th of August, 1819, to the following effect :—
“When you left us, I told you that I was to sit down to my notes of the nervous system. Believe me, this is quite an extraordinary business. I think the observations | have been able to make furnish the materials of a grand system which is to revolu- tionize all we know of this part of anatomy, more than the discovery of the circulation of the blood. I have a good deal still to do. How I am to bring it forward I do not know. I think by lectures in the first place, then by a little essay explaining the out- line of a new system, and finally, by magnificent drawings and engravings of the whole nervous system. Inthe mean time I am making gigantic drawings of the nervous system for my class.”
The gigantic drawings for his class to which he alludes were large plans of the three oreat classes of
