HOUSE-MARTENS. 253 



motionless, and perhaps asleep. As fishes have no eyelids, it 

 is not easy to discern when they are sleeping or not, because 

 their eyes are always open. 



Nothing can be more amusing than a glass bowl containing 

 such fishes : the double refractions of the glass and water 

 represent them, when moving, in a shifting and changeable 

 variety of dimensions, shades, and colours ; while the two 

 mediums, assisted by the concavo-convex shape of the vessel, 

 magnify and distort them vastly ; not to mention that the 

 introduction of another element and its inhabitants into our 

 parlours engages the fancy in a very agreeable manner. 



Gold and silver fishes, though originally natives of China 

 and Japan, yet are become so well reconciled to our climate, 

 as to thrive and multiply very fast in our ponds and stews. 

 Linnaeus ranks this species of fish under the genus of cyprinus, 

 or carp, and calls it cyprinus auratus. 



Some people exhibit this sort of fish in a very fanciful way ; 

 for they cause a glass bowl to be blown with a large hollow 

 space within, that does not communicate with it. In thig 

 cavity they put a bird occasionally, so that you may see a 

 goldfinch or a linnet hopping, as it were, in the midst of the 

 water, and the fishes swimming in a circle round it. The simple 

 exhibition of the fishes is agreeable and pleasant ; but in so 

 complicated a way, becomes whimsical and unnatural, and 

 liable to the objection due to him, 



Qui variare cupit rem prodigialitr unam. 



LETTER XCIX. 

 TO THE HON. DAINES BARRINGTON. 



October 10, 1781. 



DEAR SIR, I think I have observed before, that much the 

 most considerable part of the house-martens withdraw from 

 hence about the first week in October; but that some, the 

 latter broods, I am now convinced, linger on till towards the 

 middle of that month ; and that at times once perhaps in 

 two or three years a flight, for one day only, has shewn itself 

 in the first week in November. 



Having taken notice, in October, 1 780, that the last flight 

 was numerous, amounting perhaps to one hundred and fifty, 

 and that the season was soft and still, I was resolved to pay 

 uncommon attention to these late birds, to find, if possible, 

 where they roosted, and to determine the precise time of their 



