Page:Proceedings of the Royal Society of London Vol 2.djvu/109

Rh 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 distances; and show that, taking the stars of each class one with another, 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 ascertaining 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 arrangement 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 observations, the author is inclined to think will contain nearly all the general knowledge we can ever have of this magnificent collection of stars.

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 violence 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 common 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 peculiar mucus for the formation of the nest is secreted. Thus, says the author, the opinion which I have long