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BAUER. 
your sake and mine, that this part of the subject was covered 
by an interesting paper presented at the previous meeting 
of the Society. It was emphasized there that for the best 
results it is essential that the investigator be able to work 
with instruments so constructed as to permit him to control 
or renew the various adjustments without the necessity of 
returning the instrument to the maker. The principle at 
times employed, which assumes that when adjustments are 
once made they are to “remain put,” is a very pernicious 
one. A number of very interesting examples from my own 
experience in the purchase and manufacture of magnetic 
instruments during the past ten years might be cited; but, 
as has been said, this part of the subject having already been 
covered, there is no need to dwell further upon it than to 
emphasize the injunction that the research worker, if he 
desires the best results, must know his instruments as 
thoroughly as himself. 
Subjects of Research. 
We come next to a brief consideration of the subjects of 
research, though not specifically mentioned in the title of 
our paper, yet implied in it. The rapid progress made by 
a science as soon as it reaches the stage of experimentation 
has already been noted. A crucial experiment has at times 
furnished information which by mere observation of phe- 
nomena, running their natural and unmodified course, 
might either have never come into our possession or at best 
would have taken a considerably longer time than that of 
the decisive experiment. You are all familiar with such 
cases, for almost every science can furnish examples. 
Now it is an extremely interesting and suggestive fact that 
the greatest experimental discoveries today are not made in 
the older, well-recognized sciences, but on their border- 
lands — in the “twilight zone” of more or less related sciences. 
I have but to mention the words “physical chemistry,” “phys- 
ical geology,” “astrophysics,” “biochemistry,” etc., and you 
will readily grant the assertion made. In the overlapping 
regions there seem to be the greatest opportunities afforded 
