THE ART OF WEIC4HING AND MEASURING. G05 



F. Baily aud Doukin ; aud with Kater's Royal Society jard by Captain 

 Kater in 1831. On October 16, 1834, the Imperial standard (Bird's 

 standard of lldO) was destroyed by the burning of the houses of Parlia- 

 ment, in which it was lodged, and very soon thereafter the Lords of the 

 Treasury took measures to recover its length. Preliminary inquiries 

 were begun on May 11, 1838, and on June 20, 1813, they resulted in the 

 appointment of a commission to superintend the construction of new 

 Parliamentary standards of length aud weight; among whose members 

 the Astronomer Royal (now Sir George B. Airy), Messrs. F. Baily, 

 II. Sheepshanks, and Prof. W. H. Miller were prominent. The labori- 

 ous investigations and experiments carried out by that commission can- 

 not be described here, but it will suffice to say that for determining the 

 true length of the new standard Mr. Sheepshanks employed a pro- 

 visional yard, marked upon a new brass bar designated " Brass 2," 

 which he compared as accurately as possible with Sir George Shuck- 

 burgh's scale, the two Ordnance yards, and Kater's Royal Society yard. 

 The results in terms of the lost Imperial standard were as follows : 

 Brass bar 2 = 36. 000084 from coinparisou with Shuckbnrgh's scale, 0-36 inch. 



36. 000280 from comparison with Shuckburgh's scale, 10-46 inch, 



36. 000:503 from comparison with tlie Ordnance yard, lA. 



36.000275 from comparison witli the Ordnance yard, 2A. 



36. 000229 from Captain Kater's Royal Society yard. 



Mean = 36. 000234 



Respecting this mean Mr. Sheepshanks wrote: "This should be 

 pretty IfiBar the truth; but I prefer 36.00025, if in such a matter such a 

 difference be worth notice. I propose, therefore, in constructing the 

 new standard to assume that — 



" Brass bar 2= 36.00025 inches of lost Imperial standard at 62° Fahr." 

 And upon that basis the standard now in use was constructed.* 



Turning now to the French standards of length, it is known that the 

 ancient toise de magons of Paris was probably the toise of Charle- 

 magne (A. D. 712 to 811), or at least of some Emperor Charles, and 

 that its ('talon was situated in the court-yard of the old Chatelet, on the 

 outside of one of the pillars of the building. It still existed in 1714, 

 but entirely falsified by the bending of the upper part of the pillar. 

 In 1668 the ancient toise of the masons was reformed by shortening it 

 five lines ; but whether this reformation was an arbitrary change, or 

 merely a change to remedy the effects of long use and restore the etalou 

 to conformity with .some more carefully j)reserved standard, is not 

 quite clear, t These old e^a/on.s* were iron bars having their two ends 

 turned up at right angles so as to form talons, and the standardizing of 

 end measures was effected by fitting tliem between the talons. Being 

 placed on the outside of some public building, they were exposed to 

 wear from constant use, to rust, aud even to intentional injury by ma- 



45, p. 6G4. T 1, p. 536 aud 2, p. 395. 



