92 THE MICROSCOPE. 



vinegar that was sold. The practice was one that ought clearly to 

 be put a stop to. The mere fact of the practice having crept into 

 the trade at Glasgow was certainly no reason why he should not con- 

 vict in this case, but rather a reason that the practice, which was a 

 bad one, should be put a stop to. The practice simply amounted to 

 this, it was sailing under false colors, and selling an article under a 

 misleading name. — Glasgoiv Herald. 



Fine Rulings. — We recently referred to "Fasoldt's Test 

 Plate," which it was then claimed contained lines ruled at the rate 

 of 1,000,000 to the inch. 



Dr. R. H. Ward, of Troy, N. Y., writes upon the subject as 

 follows: — 



"In speaking of the modern microscopic rulings on glass, which 

 have been regarded with so great and deserved an interest by all 

 physicists, one cannot be careful to discriminate fully between those 

 that are known to be ruled and those whose ruling has been attempt- 

 ed but not yet demonstrated. It is self-evident that, in attempting 

 to rule lines 5,000,000 to the inch, a band may be produced which 

 does not consist of lines of that degree of fineness. There is no 

 difficulty in arranging a machine to draw lines, theoretically, of any 

 required degree of closeness. The register of a ruling engine can be 

 so arranged and subdivided as to indicate a spacing at the ruling 

 point of one ten-millionth of an inch as easily almost as of one-tenth 

 of an inch; but it may well be doubted whether such fine motion is 

 actually imparted to the diamond point, or could be recorded upon 

 the surface of the glass. It is becoming common to hear the higher 

 bands of Mr. Fasoldt, claiming up to 10,000,000 lines to the inch, 

 spoken of as actually ruled, and only waiting an objective to reveal 

 them. Such an error, made inadvertently by persons who would 

 avoid it by a little reflection, as made in the last number of one of 

 the most popular microscopical journals, gives a la.sting as well as 

 erroneous impression to non-scientific persons. Mr. Fasoldt's rulings 

 are certainly remarkable, and the lower bands are ruled with great 

 success; but how far up the scale they continue to be ruled as dis- 

 tinct lines is certainly at this time an undecided question." — Royal 

 Microscopical Journal. 



