52 
SCIENCE. 
A PLEA FOR THE METRIC SYSTEM IN 
MICROSCOPY. 
By R. H. Ward, M. D., Pres. Am. Soc. of Micr. 
One of the most important questions, theoretical and 
practical combined, which is now fairly before the micros- 
copical world and still in an unsettled state, is that of gain- 
ing definiteness and uniformity in micrometry. In this field 
emergencies have arisen during the past year which have 
compelled me to take considerable responsibility, as well as 
to perform a large amount of work, trusting that the gene- 
rous approval of my colleagues would accept and ratify 
what seemed at the time, and what seems now, most con- 
sistent with the interests of science and the dignity of this 
body. It will be remembered that a year ago, just at the 
close of our Indianapolis meeting, resolutions were offered 
favoring the metric system for micrometry, and the one 
hundredth of a millimeter as the unit to be employed, inviting 
foreign co-operation, and accepting an offer of standard 
micrometers from Prof. William A. Rogers, of the Astron- 
omical Observatory of Harvard University. None of these 
points, save the last, were new or unconsidered. They had 
been studied at leisure for years by many members who were 
present. The metric system had been adopted by all the world 
except Russia, England and the United States; and its univer- 
sal adoption was, as a rule, earnestly desired and favored by 
the educated and scientific classes. It had been adopted, or 
recommended, after mature deliberation, by the National 
Academy of Sciences, the American Metrological Society, 
the American Association for the Advancement of Science, 
by the American Society of Civil Engineers, the United 
States Coast Survey, the United States Marine Hospital 
Service, the American Medical Association, the Congress 
of Ophthalmologists, and by the largest State and local 
Medical Societies and by leading Medical Schools and 
journals, by numerous Boards of Education, College 
Faculties and local Scientific Societies, and by experts in 
i arious branches of science and art. On the other hand the 
tesolutions contained some minor faults, mostly in matters 
of taste or tact, which could have been easily remedied by 
reference to a committee. But there was no time for refer- 
ence or for adequate discussion, and rather than discourage 
their object by failure or postponement, they were adopted 
and referred to the local Societies for consideration. They 
were passed unanimously, at a small session, it is true, but 
by the same vote which established this society and author- 
ized its meeting here to-day. As too often happens, their 
incidental faults attracted more attention than their really 
scientific object. The unit proposed was evidently too 
long for integers and too short for fractions, and unlikely 
to receive a single approval either at home or abroad ; the 
proposal of international action, though its object was uni- 
versal^ approved, was in a form not likely to accomplish 
that object ; and the liberal offer of Prof. Rogers was wholly 
misunderstood and perverted, until it took the form of the 
preposterous statement that it was proposed to make Prof. 
Rogers’ micrometers standard as distinguished from those 
of other (!) makers, not the least amusing of all the blunders 
and absurdities of this precious statement being that of 
bringing the association, in any manner, by trade rivalry 
or mercenary considerations in relation with the work 
of one of our most generous scientists who has freely 
shared with the public every result of his labors, while 
pursuing them at an extravagant cost, and without a 
thought of pecuniary return. It soon became evident 
that an organized treatment of the subject was required 
to secure a proper and unprejudiced discussion of the 
objects of the resolutions. Feeling much responsibility as 
the presiding officer of this Society, and of one of the 
oldest of the local Societies, but having no authority to ap- 
point an evidently necessary committee that should repre- 
sent not only this Society but also sections of the country 
not yet named upon our rolls, I brought the subject before 
our local Association, and we invited all the Societies that 
could be reached to join with us in the selection of a 
National Committee for the consideration of this subject. 
The response from the large and active Societies, and from 
distinguished individuals, was a cordial and almost unani- 
mous approval. Many of the Societies nominated to the 
committee members distinguished as specialists in this 
branch of microscopy ; both Societies and eminent scientists 
contributed valuable opinions upon all the points at issue ; 
and a large committee was organized which will, at a proper 
time, tender a report of progress to this Society. And 
while speaking of this committee, I will take the liberty of 
saying that it would be a pleasure to me, and I doubt not to 
all of us on this side of the lakes, if our friends from Tor- 
onto or Montreal, or any other points in the Dominion which 
may be represented here, would nominate members, and 
thus make it an American instead of a national body. lo 
prevent confusion or misapplication of the practical sug- 
gestions which follow, and which naturally belong to this 
time and place, it is necessary to anticipate the report of the 
committee so far as to say that it will recommend to this 
Society to rescind its approval of the one-hundredth of a 
millimeter as the unit of micrometry, and to so modify the 
forms of the other resolutions as to leave the important 
questions of accurate measurement and convenient and 
scientific nomenclature in a favorable form for the attain- 
ment of valuable results. 
Whether this Society, as such, shall continue to be known 
as actively interested in this reform, it is for you to say ; 
though I sincerely hope that the members will unanimously 
agree with me in judging that it ought to do all that its in- 
fluence, without dictation, can do in this direction. But I 
for one do not deem the decisions of Societies or other cor- 
porate bodies decisive and final. I am not much elated by 
their approval, or discouraged by their opposition. I have 
an average amount of respect for the motives but not for the 
efficiency of legislation. In State, in Church, in Science, 
it is possible and easy to carry out laws about in propor- 
tion as they are unnecessary. People who do not need 
government are easily governed. Persons who appreciate 
authenticated micrometers will use them if they can, with or 
without the approval of societies ; and those who do not 
desire them will be about as little controlled by official 
decisions. While the encouragement and support of 
Societies and officials are welcome and valuable as far as it 
extends, I have more faith in the power of individual in- 
fluence, and to that I look for an example which is able to 
settle this question beyond appeal. 
In our micrometry we have the anomaly of a system of 
work capable of a precision almost, if not quite, unknown 
elsewhere to human art, for what other wholly artificial pro- 
cedure possesses a demonstrated limit of accuracy inside 
of the 1-300, oooth of an inch, and yet, until now, we have 
made no reasonable effort to free ourselves from avoidable 
errors known to be many times larger than that amount. 
While coal at $4.00 a ton and muslin at six cents a yard are, 
or at least pretend to be, measured with apparatus that has 
been carefully verified by standards of known quality, we 
have been measuring spaces almost infinitessimally small 
by standards of only commercial quality and possessed of 
manifest and uncorrected errors. This fact is too sugges- 
tive of the days when micrometers consisted of grains of 
sand and clippings of wire ; with the odds against us that 
we know how to do better. Arrange your microscope so that 
it will magnify 3,000 or 4.000 times, making the one-thous- 
andth of an inch on the stage seem three or four inches 
long through the lenses, then arrange an ocular micrometer 
so that the magnified one-thousandth of an inch shall be 
covered by, for instance, one hundred divisions of the 
ocular scale, and finally ascertain exactly how many of the 
one-thousandths of an inch on that or any other plate will 
be similarly measured by precisely the same one hund r ed 
divisions above it. Judging from my experience and from 
that of others who have tried the experiment, you will 
probably find a perfectly measurable discrepancy between 
the different spaces of the same name ; so that even your 
own measurements, with the same apparatus, will not be 
comparable with each other unless, as is often done, you 
select some one average space as a basis of comparison, 
and are careful to use only that. Now we are trying to as- 
certain which of these various spaces is the correct one , 
or if not one is right, then to obtain one that shall be ; or if 
that can not be done, at least to determine a known error 
from which we can compute definite results. This is not a 
question of makers, or dealers, or trade interests in any 
form, but of unmixed and independent science. We are 
attempting to procure a standard because we need it, and 
we hope for the cordial assistance of microscopists of really 
