OBSERVATIONS 
ON THE 
MOVEMENTS OF THE HAND 
AND STATIC EQUILIBRIUM. 
By 
W. N. BULLARD, M.D., and E. G. BRACKETT, M.D. 
Reprinted from The Boston Medical and Surgical 
Journal of December 20, 1888. 
BOSTON: 
CUPPLES AND HURD, Medical Publishers 
1889. OBSERVATIONS ON THE STEADINESS OB' 
THE HAND AND ON STATIC EQUILI- 
BRIUM. 
BT W. N. BULLARD, M.D., AND E. G. BRACKETT, M.D. 
In the spring of 1886, in conversation with Dr, 
H. P. Bowditch, one of us suggested the advisability 
of some contrivance by means of which the steadi- 
ness of the hand could be readily determined. Dr. 
Bowditch thought well of the matter, and kindly in- 
vented the instrument used, and had it made at the 
physiological laboratory of the Harvard Medical 
School. For this instrument we suggest the name 
of tremograph. 
It consists essentially of a long, light, wooden 
rod, which runs through a closely fitting brass 
cylinder so hung in a vertical compass-joint on the 
top of a firm upright as to permit of movement both 
vertically and horizontally in all directions. One 
end of this rod is furnished with a thimble or some 
other contrivance for holding the finger, while to> 
the other is attached a Pfliiger's pen. Various 
weights may be attached to the rod at va- 
rious distances from its point of support, which 
of course can be varied at will, so as to keep it 
when unmoved in an absolutely horizontal position. 
The upright, made of brass, is placed in the centre 
of a rectangular wooden base, which can be moved 
backward or forward on a wooden platform with 
low, grooved sides, into which it fits closely. At 
one end of this platform is a transverse groove 
behind which rises a transverse board. This 
groove serves to hold the glass plate over which the 
paper for the tracings is stretched, while the board 
supports it behind (see figure). To the contriv- 2 
ance holding the pen is attached a string by which 
the whole can be pulled backwards when not in use, 
and this string may be fastened to a little hook on 
the rod. When in use this string is loosened, the 
penholder hangs vertically, and the pen, projecting 
horizontally, comes into contact with a sheet of 
paper, which is placed over a layer of glass so as 
to offer a surface both smooth and firm for writing. 
The finger of the person to be tested is then placed 
in the thimble, which is connected with the rod by 
a compass-joint, and the motions of the finger will 
be accurately recorded on the paper. According as 
the point of support of the rod is at its middle or 
nearer one or the other end, so will the lines on the 
paper be of the same size as the actual movement 
•or proportionately greater or less. As a matter of 
fact the tracings were magnified four times, that is, 
they were to the movements of the hand as four 
to one. 
The first experiments with this instrument were 
made in the spring of 1886, but they were too few 
to be of any positive value. The work was re- 
sumed in the winter and spring of 1887, and has 
been continued more or less steadily ever since. 
In order to give our investigations a positive 
value, it was thought best to first determine what 
position of the hand was most favorable for the 
tracing of the tremors or movements to be studied. 
For this purpose the first series of tracings were 
made. They were used only to compare the results 
obtained according as the hand was held in differ- 
ent positions. The tracings in this series were 
taken from eighty-five patients at the Boston Dis- 
pensary, and six tracings were taken from each 
patient. 
It is evident that from such subjects it would be 
i npossible to obtain a normal standard of steadiness; 
for although all due care was taken not to make 
use of any whose disease would directly affect them 
in this regard, yet any person suffering from an 
ailment severe enough to cause him to seek medi- 
cal advice could hardly be expected to produce as 
firm a tracing as in perfect health. Besides, not 
•only did the ordinary nervousness of patients at 
such a time affect the subjects, but this was greatly 
increased by their apprehension at the sight of a 
new and unknown instrument, which was frequently 3 
regarded as some modification of the electric battery, 
and momentarily expected to break out in some 
startling way. 
For this reason it was early determined to use 
these tracings only to determine the relative value 
of the different positions of the hand for our pur- 
pose. The hand was tested in three positions in 
every case - pronation, supination, and midway be- 
tween the two, both with the eyes open and with 
the eyes closed. This makes six different tests in 
each case, which for convenience have been num- 
bered in the diagrams as follows : - 
I. Pronation, eyes open. 
11. Pronation, eyes closed, 
ill. Supination, eyes open. 
I V. Supination, eyes closed. 
V. Midway, eyes open. 
VI. Midway, eyes closed. 
All the tracings taken have been divided into 
two groups. I. Stable. II. Alobile. 
In a certain proportion of cases no definite direc- 
tion was taken, but the hand remained approximately 
at the point of starting. The tracing then appeared 
as an aggregation of many intercrossing lines, and 
was not developed in any special direction, its size, 
of course, varying directly with the steadiness of 
the finger. These cases have been designated as 
stable. In all the others the hand moved in some 
general direction from the starting point, and these 
have been grouped according to the direction taken 
by the hand (the opposite of that taken by the pen), 
under the headings Up, Down, Right, and Left. 
Group I. Stable. The hand was held more or 
less firmly in the original position. It may or may 
not have been steady, but what movement there 
was was confined within very narrow limits, and 
there was no definite continuous movement in any 
one special direction. 
The relative number of tracings of this character 
obtained under each of the six conditions is repre- 
sented by the diagrams below. The two series 
represent respectively the numbers obtained when 
the right hand of the subject was tested, and when 
the left hand was used. In each series the height 
of the lines corresponds more or less roughly with 
the actual number of tracings in said series, and 
this number is noted by the Arabic figures, while 
the Roman numerals below each vertical line de- 
note the special condition under which the tracing 
as taken. 4 
3 * 11 s>| 
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Comparing the lines in each diagram, which 
represent the number of the tracings in which the 
subject's eyes were open (Nos. 1., III., V.), it is seen 
that the lines increase in height in the order named, 
and again, in those representing the number of 
tracings in which the eyes were closed (Nos. II., IV., 
VI.), a similar increase in the same order is ob- 
served. Thus the number holding the hand ap- 
proximately in the original place is smallest in the 
position of pronation, and greatest when the hand 
is held midway between supination and pronation. 
Moreover, if we compare the average excursion, in 
both vertical and horizontal directions, of tracings 
in this group in which the eyes were open, with 
those in which the eyes were closed, the hand being 
held in each case in the same position, we find that 
the loss of the control of sight is felt more in the 
position of pronation than in either of the others, 
except in that of supination with the eyes closed, 
when the lateral movement predominated. 
The following are the figures : - 
Right hand. Pronatfon, eyes open (I.) 22; eyes closed (II.) 5. 
Supination, eyes open (III.) 29; eyes closed (IV.) 9. 
Midway, eyes open (V.) 30; eyes closed (VI.) 10. 
Lefthand. ' ' (I.) 10. (IL) 2. 
(III.) 13. (IV.) 2. 
(V.)15. (VI.) 4. 
Being approximately II. 1-4 1-3 1-3 
L. 1-5 1-0 1-3 
Group II. consists of those tracings in which 
some decided movement of the lines in some par- 
ticular direction from the starting point is evident. 
In these the hand has not been held more or less 
approximately in the same position, but has moved 
gradually in one direction or another. This is 
Z 5 
entirely independent of its general steadiness or 
tremulousness (shown by the firmness of the line). 
In order to obtain the amount of movement of 
the hand from the starting point in each direction, 
that is, the total excursion, the length and breadth 
of all the tracings were carefully measured. As 
before stated, the rod was so arranged that the 
tracing was in each case four times the size of the 
actual movement. 
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The average excursion in each position for all 
tracings (Groups I. and II.) is seen in the above dia- 
gram. The measurements were taken between the 
extremes in the vertical and horizontal planes. In 
series I. III. and V., that is, those with eyes open, 
the height of the lines diminishes in the order named 
in both planes and with either hand. The same 
holds good in series 11., IV., and VI., where the 
eyes were closed, except that with the left hand 
VI. is six mm. longer than IV.; but if we add the 
averages of both dimensions VI. is less than IV. in 
all cases. 
The average excursion in both planes in milli- 
metres is as follows : - 
I. II. III. IV. V. VI. 
Eyes open, 9.8 9.09 7.6 
Eyes shut, 17.8 9.7 10.5 
Now, if we compare the relative stability, as thus 
shown, with that obtained in our previous consider- 
ation of Group I., we find it also to be least in pro- 
nation. Thus the position of pronation gives the 
greatest excursion both when all the tracings are 6 
considered, and likewise when only those of Group 
J. are measured. 
■ No attempt has been made to draw any conclu- 
sions in regard to direction in these tracings, 
as the second series was much more valuable for 
that purpose. 
As to the amount of tremor in the various posi- 
tions, no difference was detected between pronation 
and supination. In the midway position less tre- 
mor is observed. 
For these reasons the position of pronation was 
considered the most favorable for our purpose, and 
another point which influenced us- in this selection 
is that this is the position into which the hand 
most naturally falls when the arm is extended. It 
is rare that any one, when extending the arm to 
place the finger in the thimble, holds it in any other 
position than that of pronation. 
The second series of tracings, one hundred and 
eighty-five in number, were taken from men between 
the ages of twenty and thirty, who were undergoing 
a competitive physical examination and were hence 
presumably as healthy a set of individuals as could 
well be found. Nearly every form of ordinary occu- 
pation and trade was represented, the liberal pro- 
fessions, of course, excepted. The tests were made, 
previous to the physical examination, when the men 
were fresh and in good condition. The position used 
was pronation, and each hand was tested separately 
and with eyes both open and closed. Each test 
lasted thirty seconds. 
In the study of these tracings the same classifi- 
cation is used as in the previous series. They too 
are divided into the two groups of the stable and 
unstable (stationary and mobile). 
In considering the direction of the movement, it 
is evident that the tracings of Group I. can afford 
us no information ; they have therefore been placed 
in the table under the heading "stationary." 
This group is of interest mainly in reference to 
the relation between the results obtained with the 
eyes open and with the eyes closed. 
Of tracings with the right hand and with the 
eyes open it is seen that one hundred and forty-one 
(76.21 per cent.) are in this group, while of those 
with the same hand while the eyes are closed only 
twenty-six (14.05 per cent.) belong here. With the 7 
left hand and the eyes open one hundred and sixty 
(86.44 per cent.) belong in this group, but of those 
taken with the eyes closed but thirty-six (19.45 per 
cent.). 
Hence with the right hand there is a little more 
and with the left hand a little less than five times 
the control with the sight than without it. (This 
of course does not mean to imply that a given trac- 
ing with sight is five times more ""stable" than a 
similar tracing when the eyes are closed, but only 
that five times as many " stationary " tracings are 
made when the hand is aided by vision as when not 
thus aided.) 
In all the tracings of Group II. the movement 
assumes a definite direction, and in the table 
before us the direction of this movement is 
shown. The table is arranged so as to give the 
number and percentage of tracings in each direction 
in each of the four conditions. The conditions of 
the tracings are noted by the Roman numerals at 
the beginning of each line : I. right hand with eyes 
open; II. right hand, eyes closed; III. left hand, 
eyes open ; IV. left hand, eyes closed. The remarks 
at the top of the columns show the direction. Thus, 
of tracings with rhe right hand and with the eyes 
open, in nine the hand moved to the right and in 
sixteen ro the left, in nineteen downwards, in no- 
case upwards. Of those which moved to the right, 
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six moved downwards in addition and three hori- 
zontally only. The total in which the general di- 
rection of the movement of the hand was downward 
was thirty-three, upwards was three. 
In a very few cases it may be seen that the hand 
rose, but so small is their number that they are prob- 
ably due to accidental causes or to an over-estimated 
effort to prevent the hand from falling. The per- 
centage in which the hand falls is large, especially 
when the eyes are closed. In the latter case, with 
the right hand, it is nearly four times as large as 
when the eyes were open, and with the left hand 
nearly live times as large. 
When the lateral direction is considered, a more 
interesting result is observed, namely, that the ten- 
dency -of the hand is to move toward the median 
line of the body, and this is so whether the eyes be 
open or shut. 
The following figures show the number of cases 
in which the hand moved in each direction: - 
y. 
y. 
96 
y 
99 
CV'X. ' 9 
These have reference to the lateral movement 
only. Ina large proportion the direction was ob- 
liquely downward, but in a very few it was obliquely 
upward. With the eyes open only three moved 
obliquely upward, with the.eyes closed thirty-six. 
When the eyes are closed and the hand is governed 
only by muscular sense, a large percentage fall to- 
ward the middle line of the body, in the propor- 
tion of a little more than two to one. 
The number of tracings in which the hand moved 
obliquely upward when the eyes were closed is too 
small to enable us to form any definite conclusion 
in this regard, but in the larger number the tendency 
is to move in the same plane as the majority of 
those moving downwards, but in an opposite direc- 
tion. 
The figures, Diagram C, express these results dia- 
grammatical ly, giving in the centre the number of 
stationary tracings, and in the circumference those 
moving in each oblique direction. 
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The amount of deviation from the starting point 
was also considered in order to determine the rela- 
tive steadiness (stability) under the different condi- 
tions. For this purpose the greatest height and 
width of each tracing was measured. 
These measurements were as follows. Averages 
of Group I. (stable tracings) : - 
I. Right hand, eyes open. Length 6.57 mm. Breadth 5.76 mm. 
li. " eyes closed. " 5.43 mm. " 9.01mm. 
III. Left hand, eyes open. " 6.24 mm. " 5.27 mm. 
IV. " eyes closed. " 7.93 mm. " 7.43 mm. 
Group II. The tracings vary considerably in size, 
as will be seen by comparison of the extremes: - 
Position I. Length. Greatest 12.70 mm. Least 2.00 mm. 
Breadth. " 15.00 mm, " 2.75 mm. 
II. Length. " 20.00 mm. " 3.75 mm. 
Breadth. " 16.20 mm. " 4.On mm. 
III. Length. • " 12.00 mm. " 2.50 mm. 
Breadth. " 9.50 mm. " 1.50 mm. 
IV. Length. " 16.20 mm. " 3.25 mm. 
Breadth. " 15.70 mm. " 1.50 mm. 
If we compare now the average measurements of 
the tracings in both groups according as they were 
drawn with the eyes open or closed, we find a decided 
loss of control when the aid of sight is removed. 
Averages, Groups 1. and II. 
Right hand, eyes open. Length 7.70 mm. Breadth 6.30 mm. 
" eyes closed. " 12.85 mm. " 14.10 mm. 
Left hand, eyes open. " 8.42 mm. " 5.26 mm. 
" eyes closed. " 11.42 mm. " 12.99 mm. 
RESUME. 
Tn a very large proportion of cases with the eyes 
open the hand is kept approximately in the original 
position. With the eyes closed this number is 
comparatively small, being about one fifth of the 
preceding. The average excursion of the hand in 
these cases, which is a measurement of its steadi- 
ness (stability) is 6.16 mm. for the right and 5.75 
mm. for the left with the eyes open, and 7.22 mm. 
for the right and 7.68 mm. for the left with the eyes 
closed, the steadiness of the left hand being in 
oaeh case greater than that of the right. The 
tracings, however, vary very considerably, the ex- 
tremes being 2 mm. and 20 mm. in the vertical, 
and 1.50 mm. and 16.20 mm. in the horizontal, 
'planes. 
Occupation or training exerts more or less in- 
fluence on the power to hold the hands in a fixed 
position (steadily), clerks and those accustomed to 
use the hands for fine work showing more power 11 
in this respect than men accustomed to rough phy- 
sical work, as laborers, teamsters, etc. A number 
of records of professional men, not included in those 
under consideration here, show as a rule much more 
control than those of any other class examined. The 
power of control of muscular effort seems to keep 
pace with mental development. The method of 
various persons in attempting to control their 
hands during this test shows this strikingly. Per- 
sons accustomed only to rough and unskilled labor 
are. as a rule, unable to perform the more delicate 
motions, and are likewise less able to co-ordinate 
for unusual movements. 
The number of tracings in. which the hands moved 
upwards are too few to enable us to draw useful 
deductions. In the greater number the elevation was 
but slight, and may have been due to an over-esti- 
mated effort to prevent the hand from falling. 
When, however, the hand descends a strong 
tendency to fall towards the median line is ob- 
served. 
When the hand deviated considerably from the 
starting point with the eyes shut, the subject had 
as a rule no knowledge that it had done so, and 
was much surprised on opening his eyes to dis- 
cover what had occurred. 
As far as could be judged the functional dis- 
turbance arising from nervousness had no influence 
PLATE I. 
No. 1. 
No. 2 
No. 3.. 
No. 4. 12 
PLATE II. 
No. 1 
No. 2. 
No, 3. 
No. 4. 
Finger Tracings (natural size). 
Figures 1.1, I. 2, I. 3, I. 4, show an ordinary series of finger tracings, all taken from the same 
person under one of the four conditions. 1.1. Right hand, eyes opened. 2. Right hand, eyes closed. 
3. Left hand, eyes open. 4 Left hand, eyes closed. This is a typical series of the " regular" type. 
There is very little variation in the extent of the movement under the four conditions. The direc- 
tion, however, varies: 1 is indeterminate, 2 upwards and to the left, 3 and 4 upwards and to the right. 
Figures II. 1, 2, 3, 4, show another series of finger tracings taken in like manner (all from one 
person). They show well the contrast which often occurs when the eyes are open and when they 
are closed. 1 and 3 eyes open, 2 and 4 eyes closed. Control of vision apparent. 13 
to increase the deviation from the starting point in 
any special direction, though it sometimes increased 
the size of the tracings of Group I. The distur- 
bance from this cause, however, was much less than 
might at first sight be expected, the unsteadiness 
in great measure disappearing with the voluntary 
effort. In two cases, however, the disturbance from 
this cause was so great that all efforts to comply 
with the test were futile. With the attempt at mus- 
cular fixation the hand was thrown into so severe 
a spasmodic action that no control was possible. 
So far as could be determined in these cases no 
alcoholic influence and no organic disease existed. 
One of these subjects was a man who passed the 
physical examination for the police force, the other 
a woman debilitated by hard work and care. 
The tremor can be estimated only by a close 
study of the tracings. It is totally unconnected 
with their " stability," or the amount or direction 
of their deviation. There is probably no tremor 
registered by this instrument which cannot easily 
be seen, and the study of its character is complica- 
ted by the presence of the coarse movements in the 
tracing. 
Many of the fine tremors are not registered, because 
the slight support given by the thimble causes 
them to cease in the finger tested, although the 
other fingers continue their motion as before. 
Hard-working laborers present no special tremor, 
but have less "stability" than those accustomed to 
more delicate work, but such tremor as existed in 
them was not overcome by mere contact with the 
instrument. 
The emotional tremor is not a fine one. Its 
amount varies considerably with the individual, 
and frequently modifies or obscures any other tremor 
which may exist. It does not, however, seem to 
affect the control (stability) of the hand. 
HEAD MOVEMENTS. STATIC EQUILIBRIUM. 
The observations in regard to static equilibrium 
were made upon the same individuals as those 
from whom our second series of hand tracings 
was taken, that is, on healthy men who were 
undergoing a competitive physical examination, and 
whose ages were all, according to their declara- 
tion, between twenty and thirty, though it is 14 
probable that a few may h ive been somewhat above 
the specified age. The total number examined 
was one hundred and eighty-one, and they were all 
tested in regard to their relative steadiness in the 
upright position, with the eyes open and with the 
eyes shut. 
The method of examination was as follows. 
The men were made to stand with their heels to- 
gether in military attitude, and with the eyes fixed 
■on some object at a distance, yet easily seen. The 
apparatus used consisted of a square piece of board 
held in position on the head by plates of spring 
brass, and in appearance much like the cap of an 
Oxford student. On the upper surface of this 
board a paper was placed to receive the tracing. 
A horizontal rod was so arranged that it could be 
adjusted at the desired height, and to this a pen 
was secured by a hinge joint, which allowed a 
vertical motion only. In each case the time 
allowed was thirty seconds, and the pen was not 
allowed to touch the paper until a moment after 
the subject had taken the required position. The 
observation was first taken with the eyes open, and 
then, after an interval, repeated with the eyes 
-closed. 
From these experiments we obtained the follow- 
ing results. No person stood absolutely still dur- 
ing the time of the trial, but some moved much 
less than others. 
The direction of movement was as follows. With 
the eyes open one hundred and thirty-eight moved 
forward, and only thirty-five backward,- the 
remaining eight either moving laterally only, or 
the direction of movement being indeterminate. 
With the eyes shut one hundred and ten moved 
forward ami fifty-eight backward, while in eleven 
the movement was either lateral only or indeter- 
minate, or equally forward and backward. These 
figures show that the ordinary man, while standing 
unsupported, has a strong tendency to move the head 
forward slightly, and this seems to be more free to 
show itself when the eyes are open, and the person 
can perceive that he is not actually in danger of 
losing his balance, than with the eyes shut, when 
a stronger exertion may be made to keep upright. 
In regard to lateral motion, we find that with 
the eyes open eighty-five moved to the right, and 15 
eighty-six to the left, showing no preference for 
either direction. With the eyes shut, however, 
ninety-seven moved to the right, and seventy-eight 
to the left, showing a slight preponderance in favor 
of the former. Those not counted moved either 
nearly straight forward or backward, or the direc- 
tion of their motion could not be determined. 
In most of the cases however, as may be seen from 
the above, the motion was not simply an antero- 
posterior or a lateral one, but a combination of the 
two. Thus with the eyes open sixty-five moved 
forward and to the right, sixty-six forward and to 
the left, sixteen backward and to the right, eighteen 
backward and to the left. With the eyes shut, 
sixty-two moved forward and to the right, forty- 
six forward and to the left, twenty-six backward 
and to the right, twenty-nine backward and to the 
left (diagram). These figures show again the 
'66 
'76 
63 
/i 
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37 
strong tendency to move forward in each case, 
rather than bickward. They show also that this 
is less marked with the eyes shut than with the 
eyes open. With the eyes open, for those moving 
forward there is no preference shown for one side 
over the other, but with the eyes shut decidedly 
more move forward and to the right than forward 
and to the left. When moving backwards, a slight 
preference is shown, both with the eyes open and 
shut, for the left rather than the right. With the 
eyes shut there certainly appears to be a decided 
tendency to move either forward and to the right, 
or in the reverse direction, backward and to the 
left, rather than in the other diagonal,-ninety-one 16 
(55.8 per cent.) moving in the one diagonal and 
only seventy-two (44.2 per cent.) in the other. 
The foregoing figures show only the general 
directions of movement, but a number of measure- 
ments were also made to determine the position of 
the person at the end of the trial in relation to his 
position at the beginning. It was quite obvious, 
from an examination of the tracings, that the 
position at the end of the trial was not by any 
means always that furthest removed from the 
position at starting, but that, on the contrary, the 
subjects moved first in one direction, and then 
frequently backwards towards or even beyond the 
starting point,-these movements being, moreover, 
not always regular, but irregular, or more or less 
zigzag. 
The directions of the points of ending from the 
starting points were measured on the tracings in 
degrees and minutes by means of a projector, and 
the following were the results obtained. 
fn only a certain proportion of cases could the 
two points be determined with sufficient accuracy 
to admit measurement of their relative direction. 
The direction was always measured from the 
starting point, which in all cases had been marked, 
to the point of ending. It was stated, as before 
ft* 
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i. , 
noted, in degrees and minutes,- the line of the 
board pressed on the paper being taken as the 
base line. Thus any line parallel to this ran from 
0° to 180°, and its perpendicular from 90° to 270°. 
Of one hundred and twenty-five cases with 17 
the eyes open, in.which these directions could be 
accurately determined, we found that in forty 
(32 per cent.) the ending point was upward and to 
the left of the starting point, since the position of 
the head at the end of the test was forward and to 
the right of that at the beginning. In seventy 
cases (56 per cent.) the position of the head at the 
end of the time was forward and to the left. In 
only eleven cases (8.8 per cent.) was it backward 
and to the left, and in only four cases (3.2 per cent.) 
backward and to the right. 
From the same number of eases, with the eyes 
shut, we found that in forty-one (32.8 per cent.) the 
position of the head at the end of the time was 
forward and to the right of its position in the 
beginning. In fifty-three cases (42.4 per cent.) it 
was forward and to the left of its original position, 
while in eighteen cases (14.4 per cent.) it was back- 
ward and to the left, and in thirteen cases (10.4 
per cent.) it was backward and to the right. 
70 
Sy 
9/ 
& 
/J 
From these figures we see that at the end of a 
certain period (thirty seconds) in the normal man, 
standing upright and striving consciously or un- 
consciously to maintain a stable equilibrium, the 
tendency is that the head should be in front of its 
original position, and rather to the left than to the 
right. Moreover, we see here, as in our previous 
results, the greater backward tendency with the 18 
eyes shut than with the eyes open, 24.8 per cent, of 
the former to 12 per cent, of the latter, or more 
than twice as many of those with their eyes shut, 
having had their heads back of the original posi- 
tion at the end of the half-minute, than of those 
with their eyes -open. 
The second question considered in these observa- 
tions was the amount of movement. As the 
actual length of the lines could not readily be 
measured, this was determined by measuring the 
space. covered by the lines. Thus the distance 
from the lowest point directly upwards to a point 
situated on the same horizontal line as the high- 
est point, was considered as the absolute length. 
In other words, the distance between two straight 
parallel horizontal lines, the one passing through 
the lowest, and the other through the highest point, 
was considered the length ; and similarly the dis- 
tance between two straight parallel vertical lines 
drawn through the extreme points on each side 
was considered the breadth. All .measurements were 
estimated in centimetres. 
The measurements were calculated from one 
hundred and fifty cases as they came in direct 
order. 
The average length with the eyes open was 
3.764 cm., the greatest length in any one case 
9.2 cm.; .the least 0.8 cm. 
The average length with the eyes closed Was 
3.475 cm., the greatest length 8.9 cm., the least 
1.2 cm. 
The average' Breadth with the eyes open was 
1.951 cm., the greatest in any case was 5.4 cm., the 
least 0.6 cm. (three cases). 
The average breadth with the eyes closed was 
1.963 cm., the greatest 6.8 cm., the least 0.4 cm. 
From these results we can draw several conclu- 
sions. In the first place it is evident, as indeed is 
very apparent from the tracings, that the antero- 
posterior movement is, both with the eyes open and 
shut, much more extensive as a rule than the lateral 
movement. Secondly, that the antero-posterior 
movement is on the average decidedly greater with 
the eyes open than with the eyes shut, while the 
lateral movement is the same under both conditions, 
being if anything more marked when the eyes are 
closed. ' ' - 19 
In order to show the amount of variation, a 
calculation was made of the number of cases which 
were within the limits of each centimetre. 
In the following table, in the column under zero, 
is found the number of cases which measured less 
than one centimetre ; in the column headed one, 
those measuring between one and two centimetres, 
and so on. 
Table showing amount of variation in antero-posterior movement 
with the eyes open. 
0 1 2 34 5 6 78 9 
1 20 37 48 25 11 9 6.2 1 
This table reads: in one case only the length 
measured less than one centimetre; in twenty cases 
between one and two centimetres; in thirty-seven 
between two and three centimetres, and so on. 
Measurements were also made to determine the 
distance between the starting point and the point 
of ending in each case, which shows the amount of 
variation in the position of the head at the moment 
of ending from that at the beginning. The average 
in one hundred and twenty-five cases with the pyes 
open was 2.840 centimetres ; the greatest distance 
was 7.7 centimetres; the least was 0.2 (two cases). 
In the same number of cases with the eyes closed 
the average was 2.716 centimetres, the greatest dis- 
tance was 8.0 centimetres, the least was 0.3 centi- 
metre (two cases). 
CONCLUSIONS. 
I. The ordinary healthy man, when standing 
erect unsupported, has a tendency to move forward 
slightly, and this tendency seems to be more 
marked when the eyes are open. 
IT. Those in whom there is a forward movement 
with the eyes open show no preference in regard to 
the direction of the lateral movement combined 
with it, the number moving forward and to the 
right, and the number moving forward and to the 
left being nearly equal. When the eyes are closed, 
however, there is a stronger tendency to move for- 
ward and to the right than forward and to the left. 
Moreover, more persons with the eyes closed moved 
backward and to the left than backward'and to the 
right. 20 
III. The position of the head at the end of half 
a minute was found in a large majority of cases to 
be in front of the position at starting, and a larger 
number were forward and to the left than forward 
and to the right. This applies both when the eyes 
were open and when they were closed. 
IV. More than twice as many persons, when their 
eyes were closed, had their heads back of the orig- 
inal position as did with their eyes < pen. 
V. The extent of the antero-posterior movement 
was somewhat greater with the eyes open than with 
the eyes closed. The extent of the lateral move- 
ment was practically the same under the two condi- 
tions. 
VI. The average extent of the antero-posterior 
movement was much greater than that of the lateral 
movement. In the majority of persons there was 
but little individual variation in the extent of the 
movements. 
VII. The average distance of the head at the 
end of the time from its position in the beginning 
was about 2.8 centimetres with the eyes open, and 
2.7 centimetres with the eyes closed. 
We cannot conclude this paper without drawing 
attention to the very interesting article of Dr. Hins- 
dale on this subject in The American Journal of 
Medical Sciences for 1878, where the first reported 
observations on these head movements are detailed. 
PLATE III 
No. 7. 
No. 2. 21 
PLATE IV. 
No. 1. 
No. 2. 
PLATE V. 
No. I. 
JHead Tracings (natural size). 
In each case the tracings are taken from a single individual 
with the eyes open (2), and with the eyes closed (1). In all cases 
they are normal tracings. 
III. These are typical tracings, rather mobile. The direction 
of movement is rather uncommon, being in both backward and 
to the left. 
IV. Typical tracings, rather stable; direction of motion forward 
and to the left. 
V. Typical tracings, average movement; direction forward and 
to the right. 
We desire to express our special thanks to our 
friend, Dr. McCollom, to whose kindness we are 
indebted for the opportunity of making many of 
our observations, and also to Dr. Rufus A. King- 
man, to whose skill we owe the excellent photo- 
graph of the tremograph. 
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