358 Ordnance Survey Astronomical Observations. 



country the seat of disturbance, and its maximum effect, 

 may be ! 



In fact, notwithstanding what the French have been in the 

 habit of doing with their maps, and what the croakers com- 

 plained of the Government not doing here, science is not 

 far advanced enough to be able to insert the astronomical 

 latitudes and longitudes with sensible accuracy on large 

 sized maps. If, then, we see parallels of latitude represented 

 by simple straight lines, we may be certain that they are 

 wrong, i. e. t they do not represent what a perfect astrono- 

 mical instrument would shew at one place, or a terrestrial 

 measure give at another, and this, too, by a quantity that 

 would permit any amateur, with small observing means, to 

 detect apparently gross errors in the National Survey. 



The volume, therefore, published by the Ordnance, opens 

 a new and most important and difficult question, rather than 

 it settles the latitudes of the trigonometrical stations. 

 Further steps must, consequently, be taken in the research ; 

 and means must be found of reducing, in all cases, what we 

 may term the apparent) to the true astronomical latitude and 

 longitude. The present book is an exceedingly good one as far 

 as it goes, and it is not the fault of the authors that the case to 

 be investigated has proved more difficult than had been antici- 

 pated, by reason of the influence of occult natural causes ; 

 nor is it at all to their discredit, if haply with the rapidly 

 advancing improvements in astronomical instruments and me- 

 thods, some more perfect instrument still to that which they 

 employed, may now be contrived. Their work is a great ad- 

 vance on all that has previously proceeded out of their office, 

 and we must particularly admire the honesty with which all 

 the original observations are given, together with the elements 

 for their reduction, so that any person may verify the com- 

 putations ; a method of publication, the example for which 

 was mainly set by the present Astronomer Royal; and who ap- 

 pears to have advised all the proceedings in the present case. 



The men who have satisfactorily carried on the work thus 

 far are doubtless the best to continue its prosecution, and we 

 hope will do so, and have full means afforded them for fol- 

 lowing it out, through all its ramifications. Meanwhile the 



