DR PETTIGREW -ON THE PHYSIOLOGY OE WINGS. 385 



have an inclination to move in an upward direction, and require to be re- 

 strained. 



After carefully analysing the movements of the gannet's wing in the dead 

 bird, I felt deeply impressed with the necessity of studying the same movements 

 in the living one. I therefore made an excursion to the Bass Rock (North 

 Berwick, Scotland) for this purpose, in July 1870. It was breeding season, 

 and the birds were in myriads, and so tame that they wheeled around and above 

 me at distances, in some cases, not exceeding from six to eight yards. The 

 gannets which were hatching permitted me to approach within a yard 

 of them, and required to be driven from their nests by the aid of a stick. I 

 had, therefore, every facility for analysing the flight of this the most cherished 

 and beautiful of the British birds. Before proceeding to describe the results 

 of the expedition in question I may state, briefly, the measurement, weight, 

 &c, of the gannet, the movements of whose wings I have just recorded. For 

 the sake of comparison I will also give the weight and measurements of a 

 heron — this bird differing widely from the gannet in the configuration of its 

 wings. 



Measurement, Weight, fyc, of Gannet and Heron. — The following details of 

 weight, measurement, &c, of the gannet were supplied by an adult specimen 

 which I dissected during the winter of 1869. Entire weight, 7 lbs. (minus 3 

 ounces) ; length of body from tip of bill to tip of tail, 3 feet 4 inches ; head 

 and neck, 1 foot 3 inches ; tail, 12 inches ; trunk, 13 inches ; girth of trunk, 18 

 inches ; expanse of wing from tip to tip across body, 6 feet ; widest portion of 

 wing across primary feathers, 6 inches ; across secondaries, 7 inches ; across 

 tertiaries, 8 inches. Each wing, when carefully measured and squared, gave an 

 area of 19^ square inches. The wings of the gannet, therefore, furnish a sup- 

 porting area of 3 feet 3 inches square. As the bird weighs close upon 7 lbs., 

 this gives something like 13 square inches of wing for every 36^ ounces of 

 body, i.e., 1 foot 1 square inch of wing for every 2 lbs. 4^ ounces of body. 



The heron, a specimen of which I dissected at the same time, gave a very 

 different result, as the subjoined particulars will show. Weight of body, 3 lbs. 

 3 ounces ; length of body from tip of bill to tip of tail, 3 feet 4 inches ; head 

 and neck, 2 feet ; tail, 7 inches ; trunk, 9 inches ; girth of body, 12 inches ; 

 expanse of wing from tip to tip across the body, 5 feet 9 inches ; widest portion 

 of wing across primary and tertiary feathers, 1 1 inches ; across secondary 

 feathers, 12 inches. 



Each wing, when carefully measured and squared, gave an area of 26 square 

 inches. The wings of the heron, consequently, furnish a supporting area of 4 

 feet 4 inches square. As the bird only weighs 3 lbs. 3 ounces, this gives 

 something like 26 square inches of wing for every 25^ ounces of bird, or 1 foot 

 ~>\ inches square of wing for every 1 lb. 1 ounce of body. 



