36 The Ordnance Survey. 
and indeed in any of the continental surveys; and it is very 
important that none of the advantages of this superiority be 
lost through the use of imperfect, or rather, not the most per- 
fect, methods of reduction and computation. 
The contents of the present volume are sufficiently indicated 
by its title*. They include all the observations for purposes 
connected with the survey made with Ramsden’s zenith sector, 
the chef d’ceuvre of that celebrated artist. The number of sta- 
tions at which observations were made is ten, namely, Dunnose, 
Dunkirk, Greenwich (two series), Arbury Hill, Delamere, 
Clifton Beacon, Burleigh Moor, Kellie Law in Fifeshire, 
Cowhythe Hill in Banffshire, and Balta, the easternmost of the 
Shetland Islands. Those at Dunnose, Greenwich (first series), 
Arbury Hill, and Clifton Beacon were made in 1802, and 
partly published in Mudge’s “ Account of the measurement 
of an arc of the meridian extending from Dunnose in the Isle 
of Wight to Clifton in Yorkshire,” printed in the Philosophical 
Transactions for 1803, and in the second volume of the ‘Trigo- 
nometrical Survey in 1804. Those at Delamere Forest and 
Burleigh Moor were made in 1806, and partly published in 
the third volume of Survey in 1811. Of the remaining observa- 
tions, which now appear for the first time, those at Kellie Law 
and Cowhythe Hill were made in 1813, those at Balta in 1817, 
those at Dunkirk in 1818, and those at Greenwich (second 
series) in 1836. 
The reason assigned by Colonel Colby for the republica- 
tion of the observations is the following: “ As the observations 
which had been published by the late Major-General Mudge 
in 1802 (1803) and 1811 formed but a very small proportion 
of the whole body of observations, most of which remained un- 
published, and partial differences would result from the adop- 
tion of more rigid astronomical reductions, I deemed it most 
expedient to republish those observations in this volume, and 
thus to furnish a congruous work for future reference.” 
Although the practice of selecting a portion of the observa- 
tions, which we are thus informed was adopted in the early 
part of the survey, is one which cannot be too strongly dis- 
commended, it is proper to remark that the changes which 
have now been made in the amplitudes in consequence of the 
insertion of the observations which were omitted, the correc- 
tion of some errors of calculation, and the use of different ele- 
* Astronomical Observations made with Ramsden’s Zenith Sector, 
together with a Catalogue of the Stars which have been observed, and the 
Amplitudes of the celestial Arcs deduced from the Observations at the 
different Stations. Published by order of the Board of Ordnance: printed 
by Palmer and Clayton, Crane Court, Fleet Street, and sold by Mr. J. 
Arrowsmith, 10, Soho Square, and Messrs. Letts and Son, 8, Cornhill, the 
Agents for the sale of the Ordnance Maps. 1842. 
