[Proc. Roy. Soc. Victoria, 34 (N.S.), Pt. I., 1921]. 



Art. VII. — An Iiitercoiwpavison of Importaiit Standard 

 Yard Measures. 



By J. M. BALDWIN, M.A., D.Sc. 

 [Read 14th JuJy, 1921. | 



In the year 1843 a committee^ was appointed to superintend 

 the re-establishment of the standards of length and of weight 

 with a view of replacing the standards destroyed by fire in 1834. 

 Forty similar bronze bars were cast in 1845, each bar 38 inches 

 long, and one inch square in cross section. Near each end a 

 cylindrical hole half an inch .in diameter, and half an inch deep 

 was sunk, the distance between the centres being 36 inches. At 

 the bottom of each hole is a gold plug about 0.1 inch in diameter 

 with three fine lines at intervals of about 0.01 inch transverse 

 to the axis, and two lines about 0.03 inch apart parallel to the 

 axis. The distance to be measured is that between the middle 

 transverse lines measured from mid-way between the longitudinal 

 lines. 



One of these bars was taken as a reference standard, and 

 each of the others was compared with this. At the close of the 

 comparisons the bars were numbered, and the temperature at 

 which each was standard was engraved on the top surface, which 

 bore the following inscription : — 



'' Copper 16 oz. tin 2^ zinc 1 Mr. Daily's Metal No. . . . 

 Standard Yard at .... Fahrenheit. Cast in 1845. Trough- 

 tons & Simms, London." 



Bar No. 1, Standard Yard at 62.00° F. was chosen as the Im- 

 perial Standard for determining the length of the Imperial 

 Standard Yard,^ and four others as Parliamentary copies. The 

 reference yard was preserved to serve as a standard for refer- 

 ence, Avhile the remaining bars were distributed throughout the 

 world. One bar — No. 40, Standard Yard at 61.99°F. — is in the 

 possession of the Melbourne Observatory. It differs from the 

 others in that on the top surface " Experimental Bar A " is 

 engraved instead of ** Cast in 1845." No special reference is 



1. G. B. Airy, Account of the Construction of the New National Standard of Length, I'hiL 

 Trans., Vol. 147. Tart HI., 621— 7G2, 1857. 



2. Weights and Measures Act, lb78, First Schedule. 



