156 Ornithology. 



vorable circumstances, might have been led, by generalizing, to 

 anticipate the discoveries of Franklin? 



' Monsieur Rozier, in the work already quoted, recommended 

 the use of metallic conductors; and himself proved their efficacy. 

 In connection with some shelves containtng silkworms, he placed 

 thin iron wires, and carried them through the wall into a cistern 

 of water. The remaining shelves were, in every other respect, 

 similarl}^ circumstanced to these; but he uniformly found that, 

 when thus protected, the worms were decidedly more healthy and 

 active than those unprovided with conductors.' 



ORNITHOLOGY. 



NO. V. 



Nests of Birds. Most birds, at certain seasons, live together 

 in pairs, and the union generally continues while the united efforts 

 of both are necessary in forming temporary habitations, and in 

 rearing their offspring. Eagles and other birds of prey continue 

 their attachment for a much longer time, and sometimes for life. 

 The nests of birds are constructed with so much art as to baffle 

 the utmost exertion of human ingenuity to imitate them. The 

 mode of building, the materials they make use of, as well as the 

 situation they select, are as various as the different kinds of birds, 

 and are all admirably adapted to their several wants and necessi- 

 ties. Birds of the same species collect the same materials, arrange 

 them in the same manner, and make choice of similar situations, 

 for fixing the places of their temporary abodes. Wherever they 

 dispose themselves, they always take care to be accommodated 

 with a shelter, and if a natural one does not offer itself, they very 

 ingeniously make a covering of a double row of leaves, down the 

 slope of which the rain trickles, without entering into the little 

 opening of the nest that Ues concealed below. In forming the 

 nest, they make use of dry wood, bark, thorns, reeds, thick hay 

 and compact moss, as a foundation, and on this, as a first layer, 

 they spread and fold in a round form, all the most delicate mate- 

 rials, as down, wool, silk, spiders' webs, feathers and other fight 

 substances, adapted for the purposes for which they are intended, 

 and to the climate in which the nest is situated. Thus, the ostrich 

 in Senegal, where the heat is excessive, neglects her eggs during 



