LETTERS FROM THE REV. WM. DERHAM. D.D. 
185 
With 
knew of. I desire you to tell me what the name of it is. 
•our humble Services to your family, I am 
S r 
Your much obliged humble Serv 1 
W. Derham. 
This Bird is a Cock-Bird, as I saw by his Testes in taking out 
the Guts. 
S r 
The last time I was at London finding these Books & visiting 
Mr. Petiver at his own house, I borrowed them of him to enjoy the 
pleasure of perusing them, & have sent them you for the same 
pleasure your self. When you have looked them over be pleased 
to return them, as clean as may be, y 4 the sale may not be hindered, 
unless you had rather keep them at a Guinnea price : for w ch 
he in gratitude will dedicate a Plate to you, as you see he hath done 
to others. I would have visited on you my self this afternoon, but 
the preparations I am engaged in for a Funeral Sermon, will not 
permit to stir. I desire our humble services may be acceptable 
ot your self & family, being 
June 15 
S r 
Your very humble serv* 
W. Derham. 
S r 
Mar : 28 171® 
I have lately made some considerable discoveries in the Eyes 
of Birds & Fishes, & the Ears of Birds, & my Glasses being not good 
enough, nor well enough rigged I beg the fav r of you to lend me 
your Microscopes, w th their, furniture, to enable me to perfect my 
observations : w ch relate to y e Choroides of Fishes a pectinated, 
curious work, growing in the vitreous Hunt to y e optick nerve 
of Birds ; & the Tympanum Labyrinth, & other very curious and 
observeable things in the auditory organ of Birds. I here send you 
all y r Books except S r Isaac’s Opticks w eb I beg the liberty of keeping 
longer : if you have the latin-edition, I should be glad to see it, 
because it hath some things w ch this English Edit, hath not I 
fancy the Head of y e Heron affords somw 1 peculiar, their Flight 
being high, & occasions of looking in the water frequent. I wish 
therefore I had one, but can’t desire such a mischievous trouble. 
With great respect I am 
S r 
Your much obliged humble Servt 
Wm. Derham. 
The choroid gland is a vascular crescent-shaped body about 
the entrance to the optic nerve in the eye of a fish. 
The tympanum in ornithology is the labyrinth of the bottom 
of the windpipe of certain birds. 
