O. T. Mason, "Psychological Literature," The American Journal of Psychology 1.3, 1888


The accompanying cut illustrates a new aesthesiometer designed by Dr. Joseph Jastrow, of the Johns Hopkins University. The essential parts of the instrument are as follows: A base, A, to which is attached a pair of uprights, D D': a block, B, upon which rests a frame, C, for receiving the arm which is held in position by grasping the band as shown in the cut. A fine millimeter-scale, O, with two arms, P P', through which it is fastened at E at any desired angle. Upon this scale are two carriages, H H', sliding along it with as much or as little friction as is desired. At G' there is a small "knee" that can be firmly screwed and holds the points, etc., F F'; any number and size of these knees can be made. Avoer are two rods, I I', connected with two head pieces, K K', through which passes a steel rod, N. The carriage is held in a fixed position by screwing down the screws at M M', and the two points are made to touch the skin by pressing the button at L, which presses down a spring that in turn releases the points.