B1R 



BIR 



ii ; for 2 X 2 is 4, and 4 X 4 is equal to 16. 



BIQUADRATIC root of a number, is the 

 square root of its square root : thus the 

 biquadratic root of 81 is 3 ; for the square 

 root of 81 is 9, and the square root of 9 

 is 3. 



BIQUADRATIC equation, an equation, 

 where the unknown quantity of one of 

 terms has four dimensions. 



Any biquadratic equation may be con- 

 ceived as generated by the multiplication 

 of four simple equations. Thus, if* = a 

 ,r=6, x=c, x=d, or x a=0, x --=0, 

 x c = 0, x </= 0,- then will x X 

 x 6 X a- c X rf = 0, beget a bi- 

 quadratic equation. Or it may be formed 

 of two quadratic equations, as a.- 1 -f- b 

 x -f c X x 1 -H d x + e = ; or, lastly, 

 it may be produced from the multiplica- 

 tion of one cubic and one simple equation, 

 as or a X X1-+-CX 1 -f- dx -f- e=0. For 

 an account of the resolution of biquadra- 

 tic equations, see EQUATIONS. 



BJQU1NT1LE, an aspect of the planets, 

 when they are 144 degrees from each 

 other. 



BIRCH tree. See BETULA. 



BlllD, in zoology. See AVES. 



BiHD-cafc/u'wf, the art of taking birds 

 or wild fowl, whether for food, for the 

 pleasure of their song, or for their de- 

 struction, as pernicious to the husband- 

 man, &,c. The methods are, by bird-lime, 

 nets, decoys, &c. In the suburbs of Lon- 

 don are several weavers and other trades- 

 men, who, during the months of October 

 and March, get their livelihood by an in- 

 genious, and, we may say, a scientific me- 

 thod of bird-catching, which is totally un- 

 known in other parts of Great Britain. 

 The reason of this trade being confined 

 to so small a compass arises from there 

 being no considerable sale of singing 

 birds, except in the metropolis : as the 

 apparatus for this purpose is also heavy, 

 and at the same time must be carried on 

 a man's back, it prevents the bird-catch- 

 ers going to more than three or four 

 miles distance. 



This method of bird-catching must have 

 been long practised, as it is brought to a 

 most systematical perfection, and is at- 

 tended with a very considerable expense. 

 The nets are a most ingenious piece of 

 mechanism ; they are generally twelve 

 yards and a half long, and two yards and 

 a half wide; and no one on bare inspec- 

 tion would imagine thut a bird, who is 

 so very quick in all its motions, could be 

 catched by the nets flapping over each 

 oilier, till he becomes an eye-witness of 



the pullers seldom failing. The wild birds 

 fly, as the bird-catchers term it, chiefly 

 during the month of October, and part 

 of September and November, as the flight 

 in March is much less considerable than 

 that of Michaelmas. It is to be noted, 

 also, that the several species of birds of 

 flight do not make their appearance pre- 

 cisely at the same time during the months 

 of September, October, and November. 

 The pippc-t, a small species of lark, for 

 example, begins to fly about Michaelmas; 

 anil then the woodlark, linnet, goldfinch, 

 chaffinch, greenfinch, and other birds of 

 flight, succeed, all of which are not easi- 

 ly to be caught, or in any numbers at any 

 other time, and more particularly the pip- 

 pet and the woodlark. These birds, dur- 

 ing the Michaelmas and March flights, 

 are chiefly on the wing from daybreak to 

 noon, though there is afterwards a small 

 flight from two till night ; but this, how- 

 ever, is so inconsiderable, that the bird- 

 catchers always take up their nets at noon. 

 The bird-catcher generally carries with 

 him five or six linnets, of which more are 

 caught than any singing bird, two gold- 

 finches, two greenfinches, one woodlark, 

 one redpoll, yeUowhammer, titlark, and 

 aberdevine, and perhaps a bullfinch ; 

 these are placed at small distances from 

 the nets, in little cages. He has besides 

 what are called flur-birds, which are pla- 

 ced within the nets, are raised upon the 

 flur, or moveable perch, and gently let 

 down at the time the wild bird approach- 

 es them. These generally consist of the 

 linnet, the goldfineh, and the greenfinch, 

 which are secured to the flur by what is 

 called a brace or bandage, a contrivance 

 which secures the birds without doing 

 any injury to their plumage. When the 

 bird-catcher has laid his nets, he disposes 

 of his call birds at proper intervals. It 

 must be owned that there is most mali- 

 cious joy in these call-birds, to bring the 

 wild ones into the same state of captivity; 

 which may likewise be observed with 

 regaul to the decoy ducks. See DECOT. 

 Their sight and hearing infinitely excel 

 that of the bird-catcher. The instant 

 that the wild birds are perceived, notice is 

 given by one to the rest of the call-birds, 

 (as it is by the first hound that hits on the 

 scent to the rest of the pack) after which 

 follows the same sort of tumultuous ex- 

 tacy and joy. The call-birds, while the 

 bird is at a distance, do not sing as a bird 

 does in a chamber; they invite the wild 

 ones by what the bird-catchers call short 

 jerks, which, when the birds are good, 

 may be heard at a great distance. The 



