MEN

187

MEN

■fr this

manner, by the rule of proportion, every number

in th P u * u,c 1 - -

be (j; .’r a ' ) m may be found. Or if the solidity of the wall8 i 0n I) 6C * solidity of a brick, both of the same dimen-

°Perif ie < l u ? t * ent will give the number of bricks ; but thisIn not be s ^ orter tkan the above.

a boy e , a ra °n’ s Architects Assistant, is a Table similar to thatkpild escr *ked, showing the number of bricks necessary to'"sins ' 1 Wa ^’ from half a brick to two bricks and a half thickThe "J 6 ’ an< ^ fr° m one foot on the surface, to 27,000 inclusive.c° of feet goes on from unity to 100 inclusive, the

siv e tb* 'kfference being one; then from 100 to 1,000 inclu-t° 2 y (w, C ? mmon difference being 100 ; and lastly from 1,000Wt l ' nc J us i ve > the common difference being 1 , 000 .be r „ ijj ere ' s no advantage in a long table, unless the num-6 en er p ^ oun< I at once without addition, which is nottended * be case- The short Table here introduced, is ex-An t , art " er than Salmon’s, and is much more handy.lt r< j j ler Table, of the same description, was published byea< P Je ater, and assistants, in his Gentleman ’s and""mb man ’ s Complete Assistant. The progression of thettion’g 618 ex P res sing the area is exactly the same as in Sal-*°"tal r XCe I J t that the latter author’s work contains two liori-Ui e 0( .j lnes more than the former ; the one ending in 27,000,""mbe ^ ln ^>^ 00 ; and with the exception of the followingJ n s ’ a h the others correspond :leaiJb 6 ° ne 'brick column, opposite 35, Salmon has 381, andXjj t i ater 3 36, the difference is 5, but Leadbeater is right,^""dbe 6 same column, opposite 45, Salmon has 502, andfrt tj. at ? r .®h3 ; but the number ought to be 496.a "d L e ^ rick *and-half column, opposite 53, Salmon has 876,®77 j jj? heater 878 ; the true number is 876, or more nearly. In 4 hi® instance they differ but little from the truth,

i^'dbeat ° n<> ^ r ' c k c °l umn > opposite 62, Salmon has 689, and“eirig goq r hh 6 ; which are both in excess ; the true number° r I 3 tj ’Or very nearly 684. The greatest difference is 12In t | i ' at Tpadbeater is beyond the truth,f ami » r ' c k'ami-half column, opposite 84, Salmon has"He ^ Teadbeater 1380; which are both in excess; theher being 1356. Salmon, who has the greatest,

t the truth hf 33 -

^" a dbe nt Same column, opposite 97, Salmon has 1604, andb A "* £t/ 61 - 4: SilImon is "Shh

s ’hOo o , y> ln the two-and-a-half-brick column, oppositei e both !Umon has 343,087, and Leadbeater 353,087, which3 th,; re j7 as tly beyond the truth, which is 330,882. Salmontb^hese 2,205 in excess, and Leadbeater 22,205.

trmh 'f eren ces are so great, and the nearest so wide of0 gov'e tlat one must suppose, either that these gentlemen• (■" . hy no regular rule, or that they were veryn ’ °" mdeed they might have come nearer to the re-

4 5uti f h lt T 1 amere s uess -

gr " e "ces IUe * ew numbers here examined, such enormous?"te r ^ a Ppear, wliat may not be expected from the farf 4 tl W 0f them?

H '

are t ^ er h"ps happen that these differences, as they are"lost rP°| ra Phical errors ; and should this be the case,f °° ab ^ e thfit one has copied from the other. Thej s rana these works are from the second edition;‘ . ’s 1769.

%

qCr 0s , 3ate( l 1748, and Leadbeater’_...

m'h'tbir ■j^, 8 Builder's Price Booh, by Phillips, for 1811, isiq r opi Jt a ,' e ; an( I I am sorry to find, in a book of so1 l, "oti’s Utl ° n ’ tbat tbe same numbers are to be found asSol * 1 the 0n atl< I Leadbeater’s, except in the four following :

j"°>i , e 'bi'iek column, opposite 20, Crosby has 223, andl "<lV be tw v a ? beater > ea ch, 220, the true number.

^lu 10 , 0 -hHck column, opposite 300, Crosby has 6626,a "d Leadbeater, 6616, the true number.

In the two-and-a-half-brick column, first, opposite 50,Crosby has 1476, and Salmon and Leadbeater, 1478 ; but thetrue number is 1378 : Secondly, opposite 5000, Crosby has145,953, and Salmon and Leadbeater, 142,953 ; whereas thetrue number is 137,867.

These numbers are so nearly alike in the three books herementioned, that the differences appear to be no more thantypographical errors ; whence we may conclude that Lead-beater’s Assistant has been copied from Salmon’s, and theTable in Crosby’s from one of them ; for though it is muchcontracted, the errors in the numbers are the same.

If compilers in general would be at the necessary pains ofexamining what they intend to adopt, three-fourths of thebooks that are published on scientific subjects would neverhave appeared ; the far greater part of them are made fromscraps of others, and many are exactly the same in substance,only slightly varied in the arrangement, or in a single wordnow and then ; and even whole paragraphs or sections arefrequently to be met with, and sometimes whole works arecopied, without any acknowledgment of the original author.Such is the case with the three authors alluded to : neitherof the latter two takes any notice of the first; but taking itfor granted that he is right, and depending upon this, theyeach make the part thus adopted their own, little suspectingthat these antiquated works would ever undergo re-examina-tion. But happy it is for scientific subjects, and for originalwriters, that there are still some few men of principle whowill pry to the bottom of the greatest difficulties, and undergothe most laborious calculations ; and though such authors asthose referred to, may have credit in the mean time for whatthey have done, they must be ultimately exposed to thatcensure which their works so justly deserve.

There is hardly a number in the latter part of theseTables but is wrong, in some instances even to thousands :but as I have put the reader in possession of a method bywhich to examine them, he may do it at his leasure ; or hemay compare any of the other numbers with those here in-serted.

When such errors arising from carelessness, are to befound in a single Table of a Price Book, is there not reasonto suppose that in other parts, not examined, they aboundequally, and therefore create a doubt as to the degree ofdependence to be placed in any one article ? There is noman perfect ; and when different ideas crowd upon the mindof a writer at the same time, in treating of subjects thathave not been before investigated, he may inadvertentlyinsert a wrong word, or a typographical error may escapehis notice ; but in most cases this will be easily detected, asother parts of the subject will readily ascertain the author’smeaning, or otherwise it may be deduced from a palpablecontradiction in terms, where only one idea could be meant.

Table III.

Explanation. —The first vertical column contains thecontents of the wall in superficial feet, the given row thethickness in bricks and half-bricks, and the other verticalcolumns the answers.

Use. —What is the quantity of reduced brickwork in awall containing 5,348 feet superficial, and 2\ bricks thick ?

Say, 5,348 = 5,000 + 300 + 48 ; then we have by the Table

5000 will require300 „

48 ,, ,,

R. Qr. Ft.

30 2 371 3 240 1 12

In.

4

0

0

consequently 5348

32 3 5 4

99

99