SYMBOLIC NOMENCLA TURE. 1 1 1 



down, or from the smallest up. The latter is undoubtedly the 

 most natural and suggestive method, but usually becomes con- 

 fused by want of careful forethought (when starting a series) in 

 providing " gaps " for the insertion of future sizes. If a numeri- 

 cal series has been already started and become commercially 

 established, the only systematic way to insert new sizes (either 

 at the beginning or through the middle of the series) is to use 

 fractional numbers. This, though awkward in sound and appear- 

 ance, seems to be the only means of suggesting the comparative 

 size of the article by its name. The use of arbitrary higher num- 

 bers between the others is, of course, worse than no numbers at 

 all. The use of a series of letters does not supply this fractional 

 loop-hole of escape, the euphony of A-and-a-half, K-and-three- 

 quarters, etc., being somewhat doubtful. Another method in 

 much favor is the use of " fancy " names, such as " Diminutive 

 Giant," " Eureka," " Fire-fly," etc. These are far preferable to 

 confused numbers, as they are not intended to convey any ideas 

 between manufacturer and customer, and admirably succeed in 

 their purpose. All this is a very difficult subject to deal with, 

 and one in regard to which we can scarcely hope for any exact 

 system. We can but point out to manufacturers two general 

 principles to be followed : ist, of leaving abundant gaps that is, 

 let a regular series run 10, 20, 30, 40, etc., instead of I, 2, 3, 4, 

 etc. ; and 2d, of using the smaller numbers for the smaller 

 objects. The second is similar in idea to the well-known Phila- 

 delphia house-numbering system, which has worked so admi- 

 rably in practice, and which has been copied by numerous other 

 cities. 



The two foregoing paragraphs are intended respectively as but 

 casual allusions to the technical and commercial nomenclature of 

 machinery in general. The subject is too elaborate to be treated 

 at length in this paper, the main purpose of which is to set forth 

 the results of the writer's experience in establishing a system of 

 names and symbols for all the component parts, commonly 

 called " details " of machines, or, in fact, of any manufactured 

 articles. 



That some such system is necessary, no engineer who has 



