190 On the Arcs perpendicular to the Meridian, 



lately shown by Mr. Airey ; and of the arc in the mean parallel, 



as combined with the principal of these, -r^r-r. 



AVe are struck by the progress that this great question, so long 

 the subject of scientific research, is now making, when we re- 

 member that at the period at which the Pendulum experiments 

 were published, their results stood alone as an indication, de- 

 rived from an extensive combination, of a much greater Compres- 

 sion than was then almost established in the general belief; two 

 years have not since elapsed, and already closer investigation, 

 and experiments not then reported, have brought the evidence 

 of two other methods of inquiry in approximation to its own ; 

 indeed, in the present state of the inquiry, the Pendulum 

 result, which was the greatest, now appears the least. The 

 differences, however, are only of that nature and amount, that 

 WC may reasonably expect will gradually give way to the 

 further progress of experiment. The measurement of parallel 

 arcs is carrying on by the states of the continent with great 

 spirit. The Pendulum is now in the hands of almost every 

 nation. The measurement of meridian arcs alone is stationary; 

 and there can be no question that those which ha\e been 

 hitherto measured are insufficient for the determination of 

 the figure of the earth. We rejoice that in this country the 

 subject has engaged the attention of Mr. Airey ; and we 

 cannot but anticipate an increased interest in it from his 

 discussion, published in the Philosophical Transactions of the 

 past year. 



The project of measuring an arc perpendicular to the 

 meridian on the parallel which is common, or nearly so, to 

 the capitals of France and Austria, appears to have originated 

 in France ; having been made the subject of a communication 

 from the French to the Austrian government, in the year 

 1809, by which its conjoint execution was proposed, and 

 was readily acceded to on the part of Austria. 



The arc which has resulted from this proposition has its 

 western extremity determined by the meridian of the obser- 

 vatory of Brest. From thence it crosses France to Stras- 

 bourg, intersecting the meridian of Paris a few miles south of 



