OcTORER 13, 1899. ] 
level, such as would be wholly inappreci- 
able to the senses, might be detected and 
recorded. If such a system of watch were 
maintained along coasts where there is rea- 
son to believe that some rise or fall of land 
is taking place, it would be possible to fol- 
low the progress of the movement and to 
determine its rate. 
But I must not dwell longer on examples 
of the advantages which geology would gain 
from a far more general and systematic 
adoption of methods of experiment and 
measurement in elucidation of the problems 
of the science. JI have referred to a few of 
those which have a more special bearing on 
the question of geological time, but it is 
obvious that the same methods might be 
extended into almost every branch of geo- 
logical dynamics. While we gladly and 
gratefully recognize the large amount of ad- 
mirable work that has already been done 
by the adoption of these practical methods, 
from the time of Hall, the founder of ex- 
perimental geology, down to our own day, 
we cannot but feel that our very apprecia- 
tion of the gain which the science has thus 
derived, increases the desire to see the prac- 
tice still further multiplied and extended. 
I am confident that it is in this direction, 
more than in any other, that the next great 
advances of geology are to be anticipated. 
While much may be done by individual 
students, it is less to their single efforts than 
to the combined investigations of many fel- 
low-workers, that I look most hopefully for 
- the accumulation of data towards the de- 
termination of the present rate of geological 
changes. I would, therefore, commend this 
subject to the geologists of this and other 
countries as one in which individual, na- 
tional, and international cooperation might 
well be enlisted. We already possess an 
institution which seems well adapted to un- 
dertake and control an enterprise of the 
kind suggested. The International Geolog- 
ical Congress, which brings together our as- 
SCIENCE. 
527 
sociates from all parts of the globe, would 
confer a lasting benefit on the science, if it 
could organize a system of combined obser- 
vation in any single one of the departments 
of inquiry which I have indicated, or in any 
other which might be selected. We need 
not at first be too ambitious. The simplest, 
easiest, and least costly series of observa- 
tions might be chosen for a beginning. The 
work might be distributed among the differ- 
ent countries represented in the Congress. 
Each nation would be entirely free in its 
selection of subjects for investigation, and 
would have the stimulus of cooperation 
with other nations in its work. The Con- 
eress will hold its triennial gathering next 
year in Paris, and if such an organization 
of research as I have suggested could then 
be inaugurated, a great impetus would 
thereby be given to geological research, and 
France, again become the birthplace of an- 
other scientific movement, would acquire a 
fresh claim to the admiration and gratitude 
of geologists in every part of the globe. 
ARCHIBALD GEIKIE. 
RESEARCHES IN PRACTICE AND HABIT.- 
Tue object of this investigation was to 
ascertain the results of practice in volun- 
tary movements, repeating the same move- 
ments an equal number of times each day 
until approximately the highest degree of 
perfection attainable was reached. 
1. Triangular movement of the arm.—The first 
experiment consisted in tapping continu- 
ously at the corners of an equilateral 
triangle whose sides measured 20™. The 
tests each day lasted only a short time; 
they were performed from 6 to 11 days by 
seven persons. 
The results of the experiment showed 
that the greatest gains in rapidity of triang- 
ular movements of the hand as well as in 
the regularity of successive movements 
were made in the early part of the practice. 
The percentage of gain in speed rapidly de- 
