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 unquestionably 
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. 
