238 Ornithology. 



what have been the effects of this operation, or whether it has 

 turned to any account, or indeed is it at all practised in Sweden" 

 or in any of the northern states where it must have been origi- 

 nally known. For this discovery however, the Swedish naturalist, 

 it is said, was raised to the rank of nobility, and otherwise liberally 

 rewarded by the states of the kingdom. 



The valve which is put on the pearl, depends on its size, color, 

 shape, and purity. The largest pearls are always held in the high- 

 est estimation, when their other" qualities are in any degree of per- 

 fection. The finest shape of the pearl must be quite globular; it 

 must be of a clear brilliant white, smooth and glossy, and entirely 

 free from spot or stain. Pearls were greatly esteemed, and much 

 sought after by the Romans. Serviha, the mother of Marcus 

 Brutus, we are informed, presented a pearl to Cassar, which was 

 valued at .50,000 lbs sterling; and Cleopatra dissolved one, which 

 is said to have been worth 2.50,000 lbs sterling, in vinegar, which 

 she drank at a supper with Mark Antony. 



ORNITHOLOGY 



NO. VIII. 



Flight of Birds. The flight of birds differs exceedmgly; 

 some fly by jerks, closing their wings every three or four strokes, 

 which gives them an undulated motion, very conspicuous in the 

 woodpeckers and wagtails, [and in most small birds; others fly 

 smooth and even; and some appear to buoy themselves in the air 

 without perceptible motion of the wings, such as the kite and 

 hawk. Most birds fly with their legs contracte(J, with their neck 

 extended; but there are some whose length and weight of neck 

 makes it necessary to contract it in flight, in order to bring the 

 centre of gravity on the wings; to aid which the legs are also ex- 

 tended behind, as^n the heron and bittern; others fly with extend- 

 ed neck, but are ob'iged to throw out their legs behind as in the 

 duck, goose, and other water fowl. 



It is recorded that a falcon belonging to Henry IV., King of 

 France, which escaped from Fontainbleau, and in twenty-four 

 hours after was found in Malta, a space computed to be not less 

 than 1350 miles, a velocity equal to 57 miles an hour, supposing 

 the hawk to have been on wing the whole time. But as such 

 birds never fly by night, and allowing the day to be at the longest, 



