586, Notices respecting New Books. 
the largest denominator, then, in a part of the arranged Table, 
15 2 13 2 QW ; é 
rophea sheet he &c.; and if the third 
: 7% 15 +13 28 
of these fractions be given, we have —-' —- = —— the second: 
es tae? 52 4.45 a7 * 
we should have 
18411 
“45 + 38 
cases, 
I am not acquainted, whether this curious property of vulgar 
fractions has been before pointed out?; or whether it may ad- 
mit of any easy or general demonstration ; which are points on 
which I should be glad to learn the sentiments of some of your 
mathematical readers; and am 
Sir, 
24 : 
= 43 the fourth of them, and so in all the other 
Your obedient humble servant, 
Howland-street. J. FAREY. 
LXXX. Notices respecting New Books. 
Ordnance Maps of British Counties. 
pe circumstances which were thought to render expedient 
the suspension of the publication of the ordnance maps being 
now removed, the publication of them is resumed, and they may 
be obtained, as formerly, at the Drawing-Room in the Tower, or 
of Mr. Faden, Charing-Cross. As the suspension was only in- 
tended to be temporary, not merely the operations of the Tri- 
gonometrical Survey, but those of the mapping and engraving, 
have been regularly carried on during that period, under the 
superintendance of Colonel Mudge ; so that several county maps 
will be ready for delivery almost immediately. The maps of 
Cornwall, Devonshire, Dorsetshire, Hampshire, (including the 
Isle of Wight,) Sussex, and that part of the county of Kent 
which squares-in on the Sussex side with the general work, will be 
published in a very few weeks: and a separate map of the Isle 
of Wight is now onsale. The maps of all the contiguous counties 
north of these are in the hands of the engravers; and that of 
the whole county of Kent is re-engraving, and in a state of for- 
wardness. When the several plots and portions now planning 
by the surveyors are finished, at least three-fifths of England 
and Wales will be ready to be placed successively in the hands 
of the engravers ; and the work will be carried on with all possi- 
ble expedition consistent with accuracy. These maps are on a 
scale of an inch to a mile, a scale that admits of an attention to 
minutize which must of necessity he disregarded in maps of smaller 
size. 
