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paflage weobferved betwixt the two Sculls was much 
larger in Singing Birds than in others that do not fing, 
fo very remarkable that any Perfon that has been but 
fliow'd this may eafily judge by the Head what Bird it 
a Singing Bird, or has aptitude thereto, tho' he never 
faw the Bird before, nor knew what Bird it were : This 
has often made me refle£t how much the Modification 
of Voices depends upon the acuracy of the Ear, and 
how deaf Perfons become dumb : And fince I have ob- 
ferved that many Children that have an acute Wit e- 
nough that are flow of Speech, that is long before they 
fpeak are much longer before they can pronounce thole 
Letters that are iharps, as g. h. r. and never have an ap- 
titude to learn to fing. Hence I judge that Songs that 
have many Sharps in them are the difficulteft to fing 
well, and difcover any Perfons Skill upon the tryal of 
Mufick moft. This I fuppofe only, having no Skill in 
Mufick my (elf, nor havingever difcourfed any Perfon 
about it, as I remember we fliow'd fome of thefe things 
to the Royal Society, and I drew fome Cuts thereof, and 
gave the Do&or upon promife that he would put thele 
and many other our joynt Obfervations in Print, but I 
hear he is fince dead. I have Anatomized moft forts of 
Creatures, and never found any Four-footed Creature 
with an Ear like a Bird, unlefs a Mole ; and a Mole has 
an Ear much like them, with a very thin double Scull, 
and great Cavity like a Bird, and is very acute of hear- 
ing, the Scull by reafon of the large Cavity is very 
fiender and eafily cruftfd, fo that a Mole is quickly kili'd 
with a bruife on the Scull like a Lark, and upon the 
bruife the Membranes oi the Scull turn black; whence 
Segerus miftake Mewlrance Cerebri in fuperficie exterior i 
omnino nigra vife : But when I have taken care not to 
bruife the Scull the Membranes were not black at all, 
both Segerus and Severinus I think had (bme perceptions 
of the different Strud'ure of a Mole s Ear, but not any 
thing 
