78 Mr, Herschel's account of a series of observations 



General of the Ordnance, under the orders of Capt. Sabine. 

 Horses, waggons, and men, were furnished for the convey- 

 ance of a tent, telescopes, rockets, and other apparatus ; and 

 four of the chronometers belonging to the Board of Admi- 

 ralty were placed at our disposal. The rockets required for 

 making the signals were furnished us from France. It would 

 have been easy, doubtless, to have procured them from the 

 Royal Arsenal at Woolwich ; but on the representation of 

 Colonel Bonne, to whom the principal direction of the ope- 

 rations in France was intrusted, it was thought more advis- 

 able to accept an offer made to us of any number which 

 might be required, prepared at Paris expressly for similar 

 operations, carrying a charge of 8 ounces of powder, the in- 

 stantaneous explosion of which, at their greatest altitude, 

 was to constitute the signals to be observed. 



Our previous arrangements being made, on the 7th of 

 July I left London; and after visiting the station pitched 

 upon at Wrotham, which was the same with that selected 

 by Capt. Kater and Major Colby, as a principal point 

 in their triangulation in 1822; and finding it possessed 

 of every requisite qualification for the purpose of making the 

 signals, from its commanding situation, being unque;stionably 

 the highest ground between Greenwich and the coast, pro- 

 ceeded to Fairlight Down, near Hastings, where I caused 

 the very convenient observatory tent, belonging to the Board 

 of Longitude, to be pitched immediately over the centre of 

 the station of 1821, which was readily found from the 

 effectual methods adopted by the gentlemen who conducted 

 the trigonometrical operations in that year, for securing this 

 valuable point. Here, on the 8th, I was joined by Capt. 



