( 890 ) 
It may not be amifs to mention here, that this Pump, which 
was ufed at the Taid New Canal, was eight foot and a half Ic^g, 
and one foot eight inches broad at the top , and about eight 
inches broad at the bottom where it is inferted in the Box, and 
did caft out eight Gallons at aftroke, and twenty one ftrokes 
being made in one m.inute, there was delivered about 169 Gal- 
lons a minutes time - whence 'tis eafie to compute, what 
quantity is thrown out in an hour. 
If it be askedj why the Pump and the Bucket is not &f the 
famebreadth throughout as high as the Bucket moveth? I an- 
fwer, that it cannot be allowed of any other fafliion than a ta- 
pering one, becaufe that thecelerity of the motion in the nar- 
rowefipartof the Pump would thereby be obftrufled irv its 
fupplying the delivery of the Water, which is thereby pro- 
vided for the evacuation anfwering to the bignefs of the upper- 
moft broader part of the Pump. 
Note, that this kindof Pumpmay by the fame contrivance be 
made of a Tree bored through with a Taper-bore;and a Basket 
may be ufed at the bottom of the Pump infteadof theBox- 
Colender, 
Some Corjftderaticns of an ohfervhg prfon in the Country upon 
Numb. 133^ of thefe tra^^iS , fent in a Letter to the Publifher 
0/ May 2^1 67 7. 
SIR, 
YOuxT:xz{kof Numh, 133. is very pleafing for the great 
variety of good Arguments, fome very cur ious,fcme very 
tifeful, all \ ery confiderable. 
I. Your Preface is brief and mode fl:. And never were noble 
Travellers betrer furnifhc with learned and accurate Inftruftl- 
ens, and with exaft and compleat Exemplars, as appears in 
ftveral of your Breviatcs. In the firfi Volume you fuggeft fome 
of the moft remarkable //;5'/^/>iV/ fjr many foreign Countries : 
You begin with Artificial InftrunientS5A"^i./'.3 i ; more parti- 
cularly for the Sea, i\/.S./>.i4o, further explained iVT". 24 ; and 
with an fnftrument for drawing any Objeft in perfpeftive , 
4«;. And v\o\\}Ar.Moxon, Mv,Seller, MuGreen^ Mr.Morden 
and othersare abundantly furniflied with Sea-plots for all Na» 
vigaxions, Projedions, Mathematical Books and Mathematical 
Inftruments for all occafions of Travellers by Sea or Land, 
Mthhsr JnacharfayUotVemosritHS, Fjfihag(^rai, nor ApoUonius^ 
