102 THE AMERICAN MONTHLY [Apr., 



except that tlie eye-piece is a 1 inch, the unit of measure- 

 ment is easily reduced to 1-430,000 of an inch. 



in the selection of the corpuscles to be measured, all 

 which are round and regular in outline and double con- 

 cave should be included. This excludes all that have not 

 filled out, all that by the absorption of too much fluid, 

 have become globular or bi-convex, and all the minute 

 blood placques, at times so common, together with white 

 corpuscles. As a practical way to eliminate any possible 

 bias, it is sometimes well not to ascertain the value of a 

 subdivision of the micrometer wheel, or of a division of 

 the glass eye-piece micrometer, until after all the obser- 

 vations are made. The measurements can be taken in the 

 units of the wheel or scale without knowing their value. 

 For instance, if a single division of the micrometer 

 wheel with a certain objective is equal to 1-960,000 of an 

 inch, and if this fact were known, there might be an al- 

 most unconscious tendency to make the readings give an 

 average above or below that figure, according as high or 

 low average would favor the theory of the case for which 

 the measurements were made. 



Now comes the important question of what value are 

 these measurements. Admitting for the purposes of the 

 argument that the proper steps have been taken for 

 macerating the clot of blood, that the proper fluid was 

 used, and that the various instrumental errors have been 

 eliminated, is the result conclusive ? There is an un- 

 fortunate misconception, particularly by lawyers of the 

 meaning of the word " scientific." It is very frequently 

 employed as synonymous with the term '• mathematic- 

 ally correct" or "universally correct." Any deduction, 

 even if not universally true, is a scientific one, if con- 

 cerned with a scientific matter, and made according to 

 the rules of logic. A conclusion is erroneously supposed 

 to be only scientific when there are no exceptions to it, 

 but unfortunately especially in medicine there are few 



