262 



were Lignieres on the French, and Fairlight Down, near Hastings, 

 on the English side. The operations at the former were made by 

 Captain Sabine and Colonel Bonne ; those at the latter by Mr. Her- 

 schel and Mr. Largeteau ; thus securing two independent lines of 

 communication, a British and a French, between the extreme sta- 

 tions, and observers at each station exchanging observations at the 

 termination of the whole operation, which was continued for twelve 

 nights, ten signals being made at each station per night ; and though 

 the whole of them could not be employed, it is stated that the final 

 result, which makes the difference of longitude between the two ob- 

 servatories equal to 9' 21 "'6, is not very likely to be found one tenth 

 of a second in error, and extremely unlikely to prove erroneous to 

 twice that amount. 



The observations are then stated in detail ; and the mode of com- 

 bining them in the most impartial manner, so as to deduce from them 

 the most advantageous result, is next investigated ; and a general 

 formula deduced applicable to all operations of the kind, and in- 

 cluding all the necessary corrections. This formula is then applied 

 to the actual observations, and the result above mentioned deduced. 

 The two results deduced by considering separately the observations 

 of the British and of the French observers, at the intermediate sta- 

 tions, exhibit a remarkable coincidence, their difference amounting 

 to only a single hundredth of a second. 



Observations on the Poison of the Common Toad. By John Davy, 

 M.D. F.R.S. Read December 22, 1825. [Phil. Trans. 1826, 

 Part II. p. 127.] 



After adverting to the correctness of the popular opinion respect- 

 ing the poisonous nature of the toad, which the professed naturalist 

 has generally rejected, the author proceeds to describe the seat of the 

 poison, which is chiefly in follicles in the cutis vera, and which, on 

 pressure, exude from it in the form of a thick yellowish fluid, which, on 

 evaporation, yields a transparent residue, very acrid, and acting on 

 the tongue like extract of aconite. It is neither acid nor alkaline ; 

 and since a chicken inoculated with it received no injury, it does not 

 appear to be noxious when absorbed and carried into the circulation. 

 Indeed, although it chiefly abounds in the integuments of the toad, 

 the author also detected it in the bile, the urine, and in small quan- 

 tity in the blood. 



Dr. Davy thinks that the principal use of this poison is to defend 

 the reptile against the attacks of carnivorous animals ; he also re- 

 marks, that as it contains an inflammable substance, it may be con- 

 sidered as excrementitious ; it may serve to carry off a portion of 

 carbon from the blood, and thus be auxiliary to the function of the 

 lungs. In support of this idea, the author observes that he finds 

 each of the pulmonary arteries of the toad divided into two branches, 

 one of which goes to the lung, and the other to the cutis, ramifying 

 most abundantly where the largest venous follicles are situated, and 



