1000000030

708 / 1042

702 G F. o M
"lel'elol'ertlVof , ¡ro'! Ihelikrover ,he o, hel' tlVo) ,
" the douhlc(ex,ant and tekfcop~ are Il,,"'cahle in a I'er·
" tical plane; and ,hen cver)' angle takeo on the limb
" (though the telefcope be never fo moch elented or
" deprdled) lVill he ao anglci" rhe pl, ne of the horizon,
" Aod this is abColutcly neeeO'Jry inplouing a horizontal
" plaoe,
" Jf the Iaods tO be plotted are hill)', ,oel not in ,oy
.. one pl. ne, the lints mea(ured cannot be down
" on paper, without hei ng redneed to vne planee, whieh
" mu!! be,he horizontal, beeaufe aotlcs are t,keo in that
" plaoe,-
" In viewiog your objeél s, if they have mueh altitude
e. ordepreffion, either wrilC down the degree and decimal
" fuewn on thedouble (ext,nt, or the I,nks Ihewn on the
" back r,de; whieh lan ("blraéled from every chain in
" the nation·line, lea,'es the length io ~IC horizont~1
.. plane, Rut if the degree is t,ken, the followlOg table
u will fuew the quantiry,
A lab" o[Ih~ /inkl lo b~ fublfanrd out o[ rv 'fy chain
in hyp&lhrnu!al lint! of f,",fal ¿,crm oltitudé, Of
¿~P"f!ion, fo r reducinc Ih(ln toh.,izontal,
D~Cfm, LinkI , IDrgrm, Linkl.\-D,-grm. Link \'
4,05-- !- 14,07 -- 3 23,074-- 8
5,73 - {\ 16'26 - 4\240495- 9
7,Dl-- í t8,r 95-- 5 25,84 --10
8, t t - I \ 19,95 -- 6 27,1 3 --1 1
,1,48-- 2 21,565-- 7 28,36 --t2
" Let the r,rn natíon Jioe really meaf"re 11°7 link!,
" and the angle of alti lUde or depreffion be IY o , 95;
" looking io ,be table you wi l! find againH 19°, V5, is 6
" link!. Now 6 times I I is 66; whieh f"brraéltJ from
" 11°7, leares 1°41, the true lensth to be I,id down
'e. io rhe pl. n.
. " Ir is ufeful in furveying, 10 take the angles, whieh
.. the bounding lioes forOl, wi,h lhe magnetie needle,
.. in arda ro c!,eek rhe angles of the figure, and to plot
" thero eoft venicntly arlerwards."
0r Ibe S'JlfaceJ ~r Bodie¡,
THF. (malldl fuperr,eial meafure with U! is a fquare
ineh ; 144 or whiehmake. a (qum fOOl. Wrigll rs make
ufe of lide in rhe mea(uriog or deals and planks; but
Ihe fquare foot which rhe glniers ufe in mcafurins of
, eoof,Os only of 61 (quare inehes. The other
me, fores are, fidl , lhe ell fquare; feeoodly, the f,lI,
conraining 36 ells; thirdly, lhe rood, eominiog
40 f,lIs ; founhly, the acre, eontaining 4 roods. SI.,(rs,
ma(oos, and paviours, ufe ,he e11 fyuare .nd rhe f, lI ; fur·
' eyor! of land ufe rhe fguare dI, rhe f,lI, ,he rood, aod
Ihe acre.
The fuperr, ·ial oICafures of lheEoglilh are, firn, rhe
fq,w e fllor; (eeondl)', ,h, ('Io"e yaed, eonlainins 9
Iquare fcer, for lheir yarJ.conlains only 3 fee!: rhirdly,
,he pille, coo,.ioing 30¡ f'luare ya rds; founhl)', rhe
lood, eonl~i"ing 40 po"s; firthly, lhe am, cont,ini"G
T R Y.
4 roods. Aod 1lCnee ir is eafy 'o reduce our (urrerficial
meafu!'cs 'o rhe Englilh, or lheir! ,<1 ours.
" In orJa lOfind rheeonreot ofa field, il is moO con·
.. venicor ro mearure rhe Jines by ti" ehaios dt(ellbed a·
.. bOI'e, p. 693 . thar of 22 yards lor eoml'uling lheI:.og.
" liOI acres, aod rhal of 24 Seots ells for ,he acres uf
"Seodaod. Theehaio is d,vided iota 100 link!, and the
ce (quare of lhe ehain is 10,000 fqua!'e links; 'eo fq uarel
" of the ehain, 01' 100,000 Iquare lioks, gil'e an acre.
"Therefore, if rhe area he cx prerred by Iqu"e IlOks,
ce divide by 100,000, or cut off r,ve decimal plaees, aotl
.. lhe quo,ient Ih, 11 give rhe ",ca in acres and deelmall
" of an acre. Wrile Ihe eorire .Ieres áparr ; bUI mlllt,·
" ply rhe decim. l! of an acre ~y 4, and rhe produél lh,1I
ce give rhe remai",!er of· Ihe area In roods and deeimals
" of a rood, Lel ,he en,ire roods be noted apm after
" ,he acres; then muhiply ,he dee;mah of a lood by 40,
" and rhe produ~ 0,,11 Sive Ih6remainder of the area 111
ce falls or polcs. Lel ,he enlire falls or poles he d,en
" writ af,er the roods, aod OIl1lriply lhe deeimals of a
" fal! by 36, if the area is required in rhe mealures of
ce Seoliand; bu, mlllliply rhe dWOIals of, pole by 30{,
" if the area is required in ,he m..fllres of I:.ngland, anJ
" ,he produél (hall Sive the reOlainder of lhe area io
ce fquare ells iD rhe former eafe, bUl in fquare yuJs in
ce rhe latrer. If, in rhe former ea(e, you 1V0uld reduce
ce the decimal! of ,he fqum e11 ro l'quare f~et', mulliply
" them by 9.50694 ; bUI, in lhe 13IIerea(e, ,hedecimal,
ce of the Englilh fq uare )'ard are reduce ro fquare fee<,
" by mulliplying Ihem by 9.
" Suppofe, for eRample, ,hat the area appears toeoo·
" t~in t2.658 4~ (qudte link! of lhe eI"in of 24 ells ;
" and that rhis area il 10 be exprefi,d in acres, roud.,
" falls, &c. of rhe meafures of Scodand. ' D,vIde rhe
" (q uare link, by tOO,OOO, and rhe quotienl 12 658.11
" fl,ows the area tocontain 12 acres ,666'oJ(}(J cf an acrC'~
"Mulriply the decimal pan hy 4, and ,h. prodult
" 2.ó3369 gives the lemainder in rood, and decimals of
" a toad. Tho(e drc,mals of rhc rood beitlg mulupl,d
" by 40, the produél gives '5. 3472 f,d ls. Mulliply,he
" deeimals 01' the 1,11 by 36, 2nd ,he produél gil'CS
" 12 '4992 (quare e1ls. The deeim,ls of Ihe fguare e11
ce mulliplied by 9.50991 gil'e 4. 7458 fq tlMt leN,
" Therefore ,he area propofed amounrs \O 12 acres, ~
ce roods, 25 falls, t2 fquare clls, ónJ 4T'o'~~~ fquare
11 fect.
" Hut if rhe area eonraios the (ame number of (qoare
" link, of Gunter's ehaio, anti is ro loe cxprentd hy
" I:.nglifll mealilles, ,he ~cres and roods are compul~d '"
" ,he (.,me manner as inthe former elle. The pob are
" eomputed as rhe r.dls. Bur rhe d~:imals of the pole,
"viz . .,l,f.~'-,;, are ro be m"ltiplieJ by 30 ~ (or :0.l5),
" and the produtl givcs 10,5029 (qllm ¡ard•. 'I'heJe'
" eimals 01' thefguar. l'"d, mul,il'l,eJ by 9, g"'e 4·51 51
" fqu are feet : Ih<tetore, in ,hls eafe, Ihe "r, is In
"Eoghfh mea(ure '2 .cres , ~ rooJs, 25 roles, 10(qu,,,
le yards . and 4.f~lt~~ f~L1arC' fl!l.!t.
" 1 he SeolS acre is tu ,he Englilh . ere, b), fl...lle,
ce as 100,000 \O 78 ,~94, ir IVe hale rl'~"J \O rhe ',Idl,"
H rence betwixt lh(! SCIHS ami Enghlh t"vO[ :;h""c: l11u1·
"tioneJ. llur it 1$ cJllomal y 11\ 10m, l""S 01 b,~I,nd
,1 lO