Part IV. Of Things relating to Mathematicty&c. %6l 
the middle of the Axletree is cut a little Box to receive the 
Wifer : from whence the Axeltree is made hollow to the end. 
In this hollow lies a JWJoofe from the Axletree,md faften d 
at one end to the Nave of the Wheel,md fo turns round with 
it. And with a Worm it hath at the other end,at the fame time, 
it turns the Perch Wheel of the Wifer, and that all the reft. Yet 
% by this meafurc, i yard will fometimes be loft in a i o o yards. 
Architecture. A Model of a Geometric^ FLAT FLOOR. 
Given by the forementioned Perfon. Contrived and deli- 
neated (a) by Dr. J. Wallis Profeftbr of Geometry at Oxford. 
Who was pleas d to give me the following Account, as an 
Abftracl" of that he hath formerly publifhed hereof, (a) M % his 
I did firft, faith the Doctor, Contrive and Delineate It in f^cap.^° 
the Year, 1644. at Queens-Colledge in Cambridge. When p r°P- I0 - 
afterwards I was made Profe(Tor of Geometry at Oxford,^' 
about the Year, 1650. I caufed it to be framed of fmall 
pieces of Wood, reprefenting fo many pieces of Timber 5 
prepar d by Mr. Rainsford a Joyner in Oxford, and put toge- 
ther by my felf. 
This I fhewed foon after to divers in Oxford, and particu- 
larly to Dr. Wilkins, then Warden of Wadham-Colledge in 
Oxford. Who was fo well pleafed with it, that he caufed 
another to be made for himfelf, according to that Pattern, 
Which he kept by him for many years, and afterwards pre- 
fented to the Royal Society. 
After the King's Reftauration , I caused another to be 
made 3 and, in the Year, 1660. prefented it to his Majefty $ 
who was well pleas 'd with it, and caufed it to be repofited in 
his Clofet. 
On the Model firft mention d, I Read two Publique 
Letlures at Oxford, on the Vefpers of the Publique Ad : the 
, one, in the Year, 1^52. as to the Conftru6tion of it 5 the 
other, in the Year, 1653. as to the computation of what 
weight every Joy nt of it fuftains 5 whereby it might be the 
better judged how far it may be fafely pra6tifed. The 
greateft weight charged on any one Joynt, doth not 
amount to Ten-times the weight of one Beam : And the 
greateft weight bor n by any one Beam 3 not to feventeen 
times its own weight : and even this, not laid all on the 
fame part, but diftributed to feveral parts of it. The fum 
ofthefetwoZe&re\? 3 is to be feen in the Sixth Chapter of 
my Book de Motu. A a a A 
