When the mètre standard was established in France, 1799, it was compared
with Sir George Schuckburg’s standard yard by Captain Kater. The
quadrant of 10,000,000 mètres, or 5,130,740 toises, was determined to
be 32,808,992 English feet, giving the mètre equal to 3·2808992 English
feet, or 39·37079 inches, and the toise equal to 6·3945925921 English
feet.
In 1814 Wollaston and Playfair, by comparison with the platinum mètre
standard at 55° F., deduced the mètre as equal to 39·3828 English inches.
During the geodetic operations of General Roy in 1802, who used 60° F.
as standard temperature, Pictet’s comparisons, using means capable of
measuring the 10,000th part of an inch, gave the mètre standard, which is
used at 32° F. as standard temperature, at 39·3828 English inches; this
corrected for temperature by Dr. Young, gave 39·371 English inches at 62°
F.; which result was confirmed by Bird, Maskelyne and Laudale.
In 1823, by Act of Parliament on report of committee, the mètre is fixed
as 39·37079 English inches.
In 1800 the Royal Society, by comparison with two toise standards sent by
Lalande to Maskelyne, deduced the mètre as 39·3702 English inches.
Later comparisons by Clarke in the Ordnance Survey Office at Southampton,
in 1866, give the mètre as 39·37043 inches.
The French Academy of Sciences by comparison with Sir George Schuckburg’s
standard at temperature of 32° F., deduced the mètre as 39·3824 English
inches, which reduced to standard temperature of 62° F., would be
39·3711, or slightly in excess of the value deduced by Dr. Young from
Pictet’s comparisons.
The legal value in England is one mètre equal to 39·37079, and the latest
reduction is 39·37043 inches by Clarke in 1866, which is probably the
most exact reduction.