\, 
1809. ] 
and dullest, and most praying, psalm- 
singing, people inthe world. What, far 
example, would have been the conse- 
quence, if your correspondent Lapicida, 
who, in your 189th Number, has amused 
(1 cannot say instructed) the public by 
writing On the theory of Arches, had de- 
Jayed his communication, until he had 
understood that theory? Why, ‘your 
wood-caiter would have been freed from 
the trouble of engraving, and you from 
the labour of examining, a very complex 
diagram; your compositor, who set up 
sheet Y, Sc awtel have had no occasion to, 
ruyn ta the case of, Greek types for Mr. 
Lapicida’s dedéa, (I am: determined nat 
to give him that trouble here,) and I 
should -haye had no oceasion to write 
pi letter. Indeed, 1 was in hopes, some 
F the celebrated matheinaticians, who 
afl write 11 your valuable Magazine, 
would have taken up, their pens on this 
occasion 3; and therefore I persuaded my 
fF grey goosequill,” to lie perdue a whole 
mouth, and wait the issue; for iris really 
a formidable ching, for an Oral fellow of a 
college, who never a Lots a pen but wheh 
he ‘signs the annual-audit-account, or 
when he.sends his antiquated maiden 
sister her quarterly remittance, to write 
a letter which the literati of the presen€ 
day, (who areas fond of skirmishing as 
the Archdukes, andthe Buobmastes. 
and, the Wellingtons, on the Continent,) 
inay., peradventure call controversial, 
Yet I do not like to see ‘any mistakes go 
uncorrected in a Magazine, with which 
I generally, so pleasantly, wear ‘away 
the otherwise dreary intervals between 
leaving the combination-room, and join- 
ing the evening whist-parties. I have, 
therefore, made up my mind to dex ne 
some mornings, (you. must know, Mr. 
Editor, that though T have some repu- 
tation for learning in ourcollege, { never 
write after dmner,) to adjusting these 
particulars. And I trust, when T inform 
Mr. Lapicida, that I stood above the_ 
fifth wrangler, the year I tock my de. 
gree, and have never lost sight of mathe- N 
matical studies for a’single week since, 
«4 (except. daring the shooting season,) that 
he will allow thayI may be able to place » 
.2 few, arguments, to’abut against his, in 
“such a way, .as to destroy the equilibrium 
Af his structure, cause - the. whole’ to 
t* sinkvat the haupches” (as the workmen _ 
call it), and fal! inge utter rain. 
° Lapicida..scems to, have thier objects 
in view, inwating his letter. dst. To 
aecuse, DB-sat au of jDisepresenis 
Hie stateinents and deductions of 
Reply to Lapicida on the Theory of Arches. 
,.tenaria, mM 
"of the piftciples of equilibration.” 
361 
David Gregory, in his paper on the Ca- 
the Philosophical Trans. 
actions, for 1697. 2. To. prove tlie 
theory of equilibration of arches, ad- 
vanced by Dr. ELlutton, to be erroneous, 
8. To describe and defend the method 
of constructing the catenaria, given by 
some author whom he does not name, ia 
a ‘© Treatise of Arches and Abutment 
Piers.” Of the author of this Treatise, 
I know nothing; Lapicida having, out of 
kindness to him, perhaps, suppressed his 
name in his communication ; but of Dr. 
Hlutton I do know, and so does all the 
public that is competent to judve, that 
he is a very excellent mathematician, 
although he has not bis name, ‘ on the 
boards,” of any of our Cambridge cole 
lege butteries. | Now Lapicida SayS, 
that when Dr. futton, in his Mathema- 
tical-Dictionary, describes Dr. Gregory 
as affirming, * that an inverted catetiaria 
is the best figure for the arch of a 
bridge,” he makes a mistatement, which 
ought to be corrected. Allow ine, then, 
to correct it, by affirming, that Dr. Gre- 
Bory, in Cor, vi. Pr. 2. of the paper 
above-mentioned, says expressly, “ None 
but the catenaria is the figure of a true 
and legitimate arch, or fornix, And 
when arches of other hgares are support 
ed, it is because in their thickness, same 
catenaria is included.” The flatter part 
of this quotation, I presume, Lapicida 
does nat undetstand; but more of that 
anon. 
Your BR eaponaee next informs us, 
that David Gregory never meant to 
speak of equel polished spheres, when he 
spoke of an inverted catenaria, as form~ 
ing an equilibrated arch. Now, on the 
contrary, I assert inost positively, and 
refer to the 6th Cor. Pr. 2. just quoted, 
in proof of my assertion, that in the ma- 
jor part of his discussion, he did mean 
equal spheres, tor he speaks of them aif 
as, “aa finitely small, rigid, and polished 
spheres,” and'that part of the corollary 
cannot be admitted as true, upon any 
other hypothesis, © than the absolute 
equality of all the spheres. So that La- 
picida ig wrong, in accusing thosé who 
really say what Dr. Gregory says, ot 
aspersipg and misrepresenting him. 
But, in the second place, Lapicida 
“complains of the theory explained and 
“defended by Dr. Hutton, as erroneous: 
“and.he exhorts his readers not to depend 
upon that theory, but to recur to “ the 
fountain-head,” that is, to David, Grego- 
ry’s paper. “to obtain “ a just knowledge 
‘Ah! 
Mr. 
