82 ANNUAL OF SCIENTIFIC DISCOVERY. 



ON A STANDARD DECIMAL MEASURE OF LENGTH FOR MECHANI- 

 CAL ENGINEERING WORK. 



The following is an abstract of a paper on the above subject, recently 

 read before the Manchester (Eng.) Mechanic's Institution, by Mr. Whit- 

 worth. The paper commenced by showing that a general desire is now ex- 

 pressed for some simpler method of measuring and computing than has 

 hitherto been the rule in mechanics and engineering. The fractional system 

 did very well in the old and cumbrous modes pursued by mechanics ; but a 

 change to some certain and easy system of measurement and notation was 

 now an absolute necessity. A decimal system was that now proposed by 

 the author for both measurement and notation, the inch being taken as the 

 unit, and divided into thousands. A workman would very soon learn to 

 think in tens, hundreds and thousands, instead of the present mode of com- 

 puting sizes, thus securing greater safety in all kinds of work which are de- 

 pendent on accuracy of size, as the manufacture of guns and warlike in- 

 struments ; and much greater accuracy in all descriptions of work. After 

 showing other advantages to be derived by the general adoption of a deci- 

 mal system of measure in all engineering and mechanical works and estab- 

 lishments, and proposing that the present measure, or rule of eighths, be 

 abandoned for a rule in thousandths, the paper concluded by showing, 

 from tables exhibited, the nature of the decimal system proposed. Mr. 

 Whitworth then showed several metal specimens of external and internal 

 gauges and sizes, arranged to a nicety, equal to l-5,000ths of an inch, on 

 the system produced. An interesting discussion followed the reading of 

 the paper, in which several gentlemen took part. Some were for adopting 

 the plan immediately, others for appointing a committee to investigate the 

 matter, or to report upon the best plan of carrying the method into practice. 

 It was ultimately moved by Mr. Fairbairn, and carried unanimously, that 

 the meeting pledged itself to the scale of one inch, and that it should be 

 divided into one thousand parts. 



On the Importance of Introducing a Neiv and Uniform Standard of Micro- 

 metric Measurement. In a paper on the above subject, before the British 

 Association, by Prof- Lyons, the author alluded to the great difficulties ex- 

 perienced by observers in enumerating, rendering, and even remembering 

 the various kinds of measures now in use in these countries and on the con- 

 tinent, portions of the English, Irish, and French inch and line, and decimal 

 parts of the French millimetre. The high figure in the denominator and 

 the number of decimal plans were exceedingly cumbrous. He (Dr. Lyons) 

 would propose that some definite micrometric integer should be assumed, 

 being a determinate part of unity. He proposed that this measure should 

 be denominated a microline. He did not mean definitely to bind himself to 

 the adoption of any standard, but would propose provisionally that the one 

 ten-thousandth part of the English inch should be assumed and denomi- 

 nated the standard microline pro tern. He would, however, have his hearers 

 bear in mind the present tendency of scientific men towards a decimal sys- 

 tem. For his own part he would prefer the French decimal scale. 



