(89«) 
KIgebra, mi other hranches of the Mathematicks W Mecbanicks, 
for the ufe ofthofe that are (li^dious in thofe Noble Arts^ well t9 
direUinthe be [I Methods, and to dete[i Erroneous adventures ^ for 
the behoof of generous Beginners^ as for the [atisfaBion and further 
encouragement of them that have attain d higher accomflifhrnents , 
Alfo, in each of ^^^/^ Volumes, hath been given the Breviate 
andSubftance of [uch Philofophical Writings^ as came abroad^ and 
mre thottght of good worth. And all along rve have interffers'^d many 
Billories^ Ph/lofophical obfervations and fromif emus Experiments, 
And now, 1 think ^ we ma) take our Proffe^fy and fee^ that we have 
got more ground in our fecond Volume than in the fir [I and more jet 
tn the third than in either of the former % whence we take the liber- 
t] to ominate well for the future, let in all this 1 a(fume nothing to 
mj felfj but give all what is due to the merits of mj generous Cor- 
reffondents. And all that have affe^tions^for Arts and Sciences may 
rejoyce to fee the Ute Proficiency of the Ingenuous and Nobler Stu- 
dents in both our famous Univci fities, and tn all the finiverftties of 
Chrifiendom. The Ingenious French have drawn the fame Toke 
with us, in publifhing their Journal des Scavans-, and the Romans 
have followed our Example in their Giornale de Letterati. And 
dmbtlefs all Civil Nations ^who have a Gufl for ufeful knowledge, 
willy in good time ^ drive en this Ex^mple-j and then^ as the Ltght 
increafeth, md rttns on^we [hall in a like proportion become fo many 
mutual Ayds to each other • And this will hopefully redound to the 
General good of Mankinds 
I doubt not but the Reader will pardon the Prolixity of this V^e- 
hcQ^ fence y as was promis' dj, it is not onely Preface^ but bears apart of 
my main b^fmefs^ which is, to excite and animate the Induflry and 
free Communications of others of feme ofwhof e Ejfe^s take for the 
J^tefent the S^^dva^m following, 
m 
The DercriptioTi 
of an Inurnment invented divers years ago % Cbriftopher 
SNxm^for drawing the Oi^t- lines ^f any Obje^ in Perfbecrive, 
Ee Fig J. wherein A, is a fraall Sight with a fliort aim B. which 
may be turn'd round about , and mov'd up and dov\1i the 
fmall Cylinder CD, which is fciewd into the piece ED,atD. this 
