77 



tent of space should contain. This arrangement is further explained 

 by reference to an annexed diagram. 



Sir William Herschel next compares the order of magnitudes with 

 the order of distances, the result of which is, that if the order of 

 magnitudes could indicate the distance of the stars, it would denote 

 at first a gradual, and then a very abrupt condensation of them ; but 

 that, considering the principle upon which the stars are classed, their 

 arrangement into magnitudes can only apply to certain relative di- 

 stances ; and show that, taking the stars of each class one with an- 

 other, those of the succeeding magnitudes are further from us than 

 the stars of the preceding order. 



In the fourth and fifth sections of this paper, the means of ascer- 

 taining the profundity or local situation of the celestial objects in 

 space, and the equalization of star light are discussed ; and these 

 are succeeded by a series of observations on the extent of natural 

 and telescopic vision, and their application to the probable arrange- 

 ment of the heavenly bodies in space. 



This paper concludes with a series of observations on the extent 

 and construction of the Milky Way ; which, with his former obser- 

 vations, the author is inclined to think will contain nearly all the 

 general knowledge we can ever have of this magnificent collection 

 of stars. 



Some Account of the Nests of the Java Swallow, and of the Glands 

 that secrete the Mucus of which they are composed. By Sir Everard 

 Home, Bart. V.P.R.S. Read June 26, 1817. [Phil. Trans. 1817, 

 p. 332.] 



After noticing the various opinions which have been entertained 

 concerning the materials of which the nests of the Java Swallow are 

 composed, Sir Everard proceeds to examine the glandular structure 

 of its oesophagus and stomach, as also the chemical characters of the 

 substance forming the nest. He was chiefly led to this inquiry by 

 the suggestion of Mr. Raffles, who was of opinion that the matter of 

 the nest was brought up from the bird's stomach, and that the vio- 

 lence of the effort was occasionally such as to be accompanied with 

 blood, the stain of which is sometimes seen on the nests. 



On examining the gastric glands of the Java swallow with a com- 

 mon magnifying glass, their orifices obviously differed from those of 

 other birds, and of the common migrating swallow of England. 



The Java swallow is a constant inhabitant of the caverns of that 

 island, and about twice the size of the common swallow. It builds 

 two nests ; one oblong and narrow for the male, the other wide and 

 deep for the female and her eggs. The peculiarity of structure in 

 the gastric glands consists in a membranous tube surrounding each 

 of their ducts, which, after projecting into the gullet, splits into 

 separate portions, like the petals of a flower. From the surface of 

 these tubes the pe.culiar mucus for the formation of the nest is se- 

 creted. Thus, says the author, the opinion which I have long 



