238 
duce the condition of a mass of gas so com- 
pressed that in spite of a very high temper- 
ature its volume is less than that of the same 
mass cooled to solidification? Yet this 
extreme of condition must be the normal 
state within the bodies of many of the stars. 
It has been aptly said that many, and 
perhaps most, of the important discoveries 
have been made with comparatively simple 
and crude apparatus. While this may be 
true, yet it is probably true also that future 
advance work is likely to require more and 
more refined means and greater nicety of 
construction and adjustment of apparatus. 
The expense or cost, if not the difficulty 
of the work, may become so great as to 
effectually bar further progress in some 
fields. When instruments require to be 
adjusted or constructed, to such refined 
limits as a fraction of a wave-length of light, 
but few can be found to undertake the 
work. The interferometer and echelon 
spectroscope of Michelson involve such 
minute adjustments that a wave-length of 
light is relatively thereto a large measure. 
It is well known that this comparative 
coarseness of light waves imposes a limit to 
the powers of optical instruments, as the 
microscope and telescope, such that no per- 
fection of proportion, construction and cor- 
rection of the lenses can remove. 
In most fields of research, however, 
progress in the future will depend in an in- 
creasing degree upon the possession, by the 
investigator, of an appreciation of small 
details and magnitudes, together with a 
refined skill in manipulation or construc- 
tion of apparatus. He must be ready to 
guide the trained mechanic and be able 
himself to administer those finishing 
touches which often mark the difference 
between success and failure. There must 
be in his mental equipment that clear com- 
prehension of the proper adjustment of 
means to ends which is of such great value 
in work in new fields. He must also learn 
SCIENCE. 
[N. S. Von. X. No. 243. 
to render available to science the resources 
of the larger workshops and industrial es- 
tablishments. 
The application of physical principles up- 
on a large scale in such works has fre- 
quently, in recent years, resulted in great 
gains to science itself. The resources of 
the physical laboratory are often relatively 
small and meagre compared with those of 
the factory. Experimental work in certain 
lines is now frequeutly carried on upon a 
scale so great and under such varied condi- 
tions as would be almost impossible outside 
of a large works. 
In no field has this been more true than 
in that of electricity during the past few 
years. We need only instance the progress 
in alternating currents and in relation to 
the magnetic properties of iron. In large 
scale operations effects which would be 
missed or remain masked in work under- 
taken upon a more restricted scale receive 
emphasis sufficient to cause them to com- 
mand attention. The obstacle of increas- 
ing costliness of equipment, which in some 
fields might act as a bar to further progress, 
can only be overcome by more liberal en- 
dowments of laboratories engaged in ad- 
vance work. Even those in the community 
who can only understand the value of 
scientific work when it has been put to 
practical use may find in the history of 
past progress that many discoveries in 
pure science which had not, when made, 
any apparent commercial importance or 
value have in the end resulted in great 
practical revolutions. ; 
Could Volta, when he discovered the pile — 
one hundred years ago, have had any idea 
of its importance in practical work? Or, 
did Davy or his contemporaries at the time 
of his experiments with the are of flame 
between the charcoal terminals of his large 
battery have any suspicion that in less 
than one hundred years the electric are 
would grow to such importance that more 
