[40.1] 
Treatife oi Jlgebra, now m the prefss\) I think their 
ufe in thefe pares to have been much ancienter. As old 
at leltasthe times of Hermanuus Contrailus ^ who lived 
about the year of our Lord loyo. (^that is, about the 
middle of eleventh Century: ) If not lo frequently in or- 
dinary affairs; yet at left in Mathematical things, and 
efpecially in Aftronomical Tables. 
They came to us , I fuppofe, firft from the Moors in 
Spain^ from whom we had our ^r/a^/J/V>^ learning, efpeci- 
\ cially the^r<?;^o;?2?V^j/.Anditmuffcneedsbe as ancient as 
I any Latino Trartjlations are out of Arabic\, of AjitQuomu 
calTables and other Ajtronomical Treaties. Which could 
neither be well underftood in Arabick^, nor tranflated 
intoLatine, without .theufeof fuch Figures : which oc- 
cur frequently in thofe Authors. 
But I do not remember, that I have any where feen 
any Monument of them more ancient than the Mantle- 
tree here defcribed. 
The fides of the Chimny, by which the Mantle-tree is 
fupporced, are of ftone: But the Mantle-tree it lelf isof 
Wood, whether of Oak, I cannot fay, or rather ("as it 
feems to me ) of fonis other hard wood, which by 
being kept pexpetually Dry, and Saioaked, is become as 
Durable. And it may yet ( for ought appears^ fo pre- 
lerved, continue for fome hundreds of years more. For 
I did not difcern in it, any thing either of Worm, or 
of Rotteonefs, or any tendency to it. 
It is all over as Black as Ink but not Gloffy i ) not fo 
painted, but having by Age and Smoke contracJted 
that colour. 
The length of it, AB, is five Foot, nine inches: Its 
Breadth or Depth, at the ends, ("asACBDjJ is one 
Foot, ( or rather eleven inches and a half;) but at the 
middle, as EF, fomewhat lefs ; being fomewhat hollow- 
ed. Arch-wife. 
It is all carved from end to end. The lower part 
of it isabated, in iike manner as in the Mouldings of 
other Chimnies. On the tront of the upper part, is, iii 
