FIG. I.-The Kinesimeter (size the original). T, Table; R, Car; N N, Endless cord; P, P', P", Grooved wheels; L, Scale; S, Adjustible support.

The car itself (Fig. II.) has the following construction. It consists of a square brass frame, 6 x 6 cms., supported on four wheels. Joining the two sides of the frame are two cross-pieces K, K', having between them a space 1 cm. wide. Within this space, and sliding by grooves along the cross-pieces K, K' is a cubical block of brass (not shown in the figure), which can thus be moved from one side of the car to the other through a distance of 4 cms. The upper side of K is marked off into millimetres, and the sliding block has on it an index; by this means the position of the block can be exactly determined. By means of the screw V, the grooves in K' can be narrowed and the cubical block thus clamped in any position desired. Through the centre

N,

FIG. II. Car (size 1). RR, Adjustible rod; A, Swinging arm; C, Counterpoise cup; T, Hollow tube (rubber tubing and flasks for keeping a continuous stream of water flowing through the tube-not shown). Clamping screw to hold R R in position; K, Cross piece with scale; K', Cross-piece, the groove of which can be narrowed; V, Clamping screw by which the

narrowing is effected; M, Clamp for fastening the endless cord to the car. FIG. III.-Hollow pointed tube (actual size). I, Inflow; O, Outflow (after Blix).

of the block runs the vertical rod R R, 10 cms. long, and rectangular in cross-section. This rod can be moved up and down, and fixed at any height by the clamping screw N (partly shown in the figure). The lower end of the rod bears the curved arm A, 8 cms. long, which swings vertically. At one end is the cup for holding a counterpoise weight; at the other the pointed tube is soldered (Fig. III.).

In Fig. I. is to be seen the support S. This is a heavy brass platform, the height and inclination of which can be adjusted within wide limits: when experimenting, a wooden trough was lashed to the top of this plate S, and in this trough the limb, supported at the sides by soft cloths, rested. Thus slight movements of the limb were prevented, and the whole plate could then be raised to the requisite height, and levelled for the experiment.

It remains to describe the device for applying the thermal stimulus to the skin. This was copied, in the later work, directly

from Blix.

A German silver tube (Fig. III.) was made in a way which is plain from the figure. Water of the requisite temperature was allowed to flow through it, entering by the straight limb, and by this means any temperature could be maintained throughout the experiment. The point of this tube which is applied to the skin, is 0.9 mm. in diameter and rounded.

The part to be examined having been adjusted on the platform S as described (Fig. I.), the car was moved along until the point of the tube was brought to rest on the desired spot. Then, supposing the portion of skin to be examined to be 2 x 3 cms., by means of the gearing above described the car was made to move over the skin in a straight line and at a slow and uniform rate; the point pressing down with a weight of about 10 grms. The distance of 3 cms. having been thus traversed, the point is raised and the car rolled back to the place from which it started. Now by means of the block which carries the rod R R (Fig. II.) the point is moved 1 mm. laterally, and the same thing repeated. Thus, in mapping out a space 2 x 3 cms., the car is drawn 21 times over the skin, making 21 parallel lines or practically touching every bit of skin within the area. The fact that the point is 9 mm. in diameter and is moved 1 mm. each time, is not inconsistent with the above statement, for the sinking-in of the skin under the point brings practically a millimetre of surface in contact with the point on each tip.

For the purpose of making it possible to continue such observations for a number of days, the hand or other part of the body was marked. To do this a point was located in the back of the hand, for instance, by very careful measurements which could be repeated at any time. In a line at right angles to the long axis of the hand, another point was marked; then in a line at right angles to the line joining these two parts, a third point was placed a few centimetres distally.

Starting from the first-mentioned point, a series of very fine dots was placed along the transverse line at each millimetre. There was thus formed a line of 21 dots along the distance of 2

cms.

The hand was adjusted so that the lines drawn by the thermal point coincided with, or were parallel to, the line at right angles to this row of dots; by means of this device it was possible to arrest an experiment at any time, and take it up again from the exact point at which it had been stopped.

The marking the skin was done with a fine brush dipped in an indelible ink. The permanency of this marking material was its main recommendation; at the same time, it may not be out of place to draw attention to the fact that the slight inflammation caused by the silver nitrate renders it unsuitable for marking the temperature-spots themselves.

The position of the spots at which heat or cold was felt, was recorded in the following way. On the car was a fine index

which moved over the millimetre scale L (Fig. I.) as the car was drawn along. The index moved 1 mm. for each mm. of skin over which the point passed, so that, if the position of the index was observed at the start, the distance through which the point had moved on the surface could at any time be readily found. Fifths of a millimetre could be read on the scale, so that the position of the point could be accurately recorded. In practice then the position of the index was noted when the point was on one of the dots on the hand. As the car moved on and a spot at which the temperature was felt was crossed, the person examined called "hot" or "cold" and the experimenter noted the position of the index. After the experiment, the positions of the spots were all calculated from these notes and recorded on paper ruled in squares on which 1 mm. was represented by 5 mms., thus enlarging the area twenty-five times. By this means, the small differences in the positions of spots could be recorded without confusion. The maps to be presented were made in this way, and then reduced to their true size, the points occurring within 5 mm. being in these maps united into a single point.

There is of course the possible source of error that, where the surface is rough, 1 mm. on the scale will not represent 1 mm. on the skin. This has been attended to, and though it prevents the use of this method of experiment on certain parts, it does not become of any importance in the maps given.

There is another error which should be noted. The points being 9 mm. wide, the lateral position of a spot is in doubt by 45 mm. All the spots are put down in the middle of the path of the point and are thus so far inexact. The relations of the spots are, I think, even under these conditions, pretty fairly represented. A number of preliminary experiments were made to see if any important variation was caused by varying the direction in which the point was drawn: the results were found the same, whether the motion was up or down the limb or transversely, so that in the later experiments it was always drawn in one direction only. There is a slight variation caused by the movement of the skin itself under the point, especially at those places where the skin is loose; but where the movement is always in the same direction, this disturbing factor is reduced to zero.

Two carefully constructed maps are given (Figs. IV. and V.) for the left and right hands of the same individual, the parts being symmetrical. In this case the cold-spots are marked with dots and the heat-spots with circles; the difference in size indicates a difference in the intensity and regularity with which the sensation could be obtained from the different spots, the smaller spots being less sensitive.

In this work the temperature of the point used for finding the spots at which cold was felt, was about 15° C., while that for the heat-spots was about 50° C. In the study of the spots on other parts of the skin, the metal tube of Blix was often held in the

hand and thus moved about, this method answering for certain work very well. The other apparatus used will be described

further on.

FIG. IV.-Map of the heat-spots and cold-spots on the back of the left hand. Extent, 2 x 3 cms. Dots indicate cold; circles, heat; the larger ones represent the spots which give a strong reaction; the smaller, those which give a weak one. The top of the map is peripheral, the bottom central. The right side is the radial; the left the ulnar.

FIG. V. Similar map for the symmetrical portion of the right hand of the same individual. In this case, of course, the left side is the radial, and the right the ulnar.

In the statement of results it will be necessary to give them in chronological order to show how far they were independent. When first experimenting, a cold brass point, 1.5 mms. in diameter, was the only instrument used. With this I had found that cold was felt in spots, some spots giving an intense sensation, others a weak one; that the skin between these spots was not sensitive to cold; that the points were differently distributed in different parts of the same individual, and in similar parts of different individuals; that they were very small-as shown by the fact that unless a spot was carefully marked it could not be easily found again, for passing the point even very close to it did not rouse a sensation, as a rule; that they were permanent-once having been found they always could be found again; that they were easily exhausted-this being shown by the fact that, when the metal point was drawn down the arm and a certain number of points were observed, if it was again drawn down immediately, the number noticed on the second trip was almost always less than on the first, but if some minutes were allowed to elapse between the two trips, then the second result was, as a rule, like the first. When I had gone thus far, Blix's paper was received. Blix (1), besides noting all the points above mentioned, found similar spots for heat, and found that what was true of the cold-spots was true of the heat-spots also, so far as their arrangement and distribution were concerned. He noticed also that the arrangement on symmetrical parts was not symmetrical; that the rela