p o s 
V o s 
? >nny-post, which, since the abolition of Mr. 
'aimer’s appointment of surveyor and compt- 
roller-general, has been new modelled and 
greatly improved in all its branches. There 
is likewise a postmaster-general of Scotland, 
with a secretary, comptroller, surveyors, and 
a separate establishment of all the requisite 
officers and clerks at Edinburgh, acting under 
the orders of the joint postmasters-general in 
London. The annual expence of manage- 
ment is about 150,000/. and the gross pro- 
duce exceeds 700,000/. a year. 
For the present rates of postage, and the 
laws respecting franking, see Letter. 
No action can be maintained against the 
postmaster-general for the loss of bills or ar- 
ticles sent in letters by the post, and lost. 
Many attempts have been made by post- 
masters in country towns, to charge an half- 
penny or penny each letter, on delivery at 
the houses in the town, above the parliament- 
ary rates, under pretence that they were not 
obliged to carry letters out of the office 
gratis ; but it has been repeatedly decided, 
that such demand is illegal, and that they are 
■bound to deliver the letters to the inhabitants 
within the usual and established limits of the 
town, without any addition to the rate of 
postage. 5 Bur. 5709. 
Post tivo-penny, a post established for the 
benefit of London, and other parts adjacent, 
w hereby any letter or small parcel is speedily 
and safely conveyed to and froiii all places 
within the bills of mortality, or within ten 
miles of the city. It is now managed by the 
general post-office, and receiving-houses are 
established in most of the principal streets 
for the more convenient transmission of the 
letters. 
Letters were originally conveyed by this 
office at the rate of one-penny ; but the rate 
has been lately raised to two-pence, and for 
letters off the stones the rate is three-pence. 
Post, a particular mode of travelling. A 
person is said to travel post, in contradis- 
tinction to common journey travelling, when, 
in place of going on during his wholejourney 
in the same vehicle, and with the same 
horses, he stops at different stages, to pro- 
vide fresh horses or carriages, for the sake of 
greater convenience and expedition. As lie 
thus uses the same mode of travelling that is 
employed for the common post, he is said 
to travel post, or in post, i. e. in the manner 
of a post. 
In tracing the origin of posts, it appears 
that the more antient establishments of this 
kind were fully as much for travelling sta- 
tions as the conveyance of letters. The re- 
lays of horses provided at these public sta- 
tions for the messengers of the prince, were 
occasionally, by special licence, allowed to 
be usedby’other travellers who had sufficient 
interest at court. Frequent demands of tills 
nature would suggest the expedient of having 
in readiness supplies of fresh horses or car- 
riages over and above what the public service 
required, to be hired out to other travellers 
on payment of an adequate price. We find, 
therefore, that in former times, the post- 
masters alone were in use to let out horses 
for riding post, the rates of which were fixed 
in 1548, by a statute of Edward VI., at one 
penny per mile. In what situation the state 
of the kingdom was with regard to travelling 
post for more than a century atter this period, 
we cannot now certainly discover ; but in 
Vol. IF 
the statute re-establishing the post-office in 
1680, it is enacted, that none but the post- 
master, his deputies, or assigns, shall furnish 
post-horses for travellers; with a proviso, 
however, that if lie has them not ready in 
half an hour after being demanded, the tra- 
veller shall be at liberty to provide himself 
elsewheie. The same prohibition is contain- 
ed in the act establishing the Scots post-office 
in 1695, as well as in the subsequent act of 
queen Anne, erecting the general office for 
the united kingdom. It is doubtful, however, 
whether it ever was strictly enforced. By an 
explanatory act of 26 Geo. II. the prohibition 
is confined to post horses only, and every 
person declared to be at liberty to furnish 
carriages of every kind for riding post. This 
regulation has, in fact, done away the pro- 
hibition, as hardly any person now thinks of 
travelling post, except in a carriage. 
The rate fixed by the act 1695, in Scotland, 
for a horse riding post, was three-pence per 
Scotch mile. By the act 9. Anne, c. 10. 
three-pence a mile without, and four-pence a 
mile with, a guide, was the sum fixed for each 
horse riding post. The increase of com- 
merce, and necessity for a speedy communi- 
cation between different parts of the king- 
dom, have brought the mode of travelling 
post so much into use, that upon every great 
road in the kingdom, post chaises are now in 
readiness at proper distances ; and the con- 
venience of posting is enjoyed in Britain to a 
degree far superior to what is to be met with 
in any other country whatever. 
Posting at last appeared to the legislature a 
proper object of taxation. In 1779 the first 
act was passed, imposing duties on horses 
hired either by themselves or to run in car- 
riages travelling post ; the duties were, one 
penny per mile on each horse if hired by the 
mile or stage, and one shilling per day if hired 
by the day. Every person letting out such 
horses was also obliged to take out a licence 
at five shillings per annum. These duties 
were next year repealed, and new duties im- 
posed, of one penny per mile on each horse 
hired by the mile or stage, and one shilling 
and six-pence on each if hired by the day. 
A number of additional regulations were at 
the same time enacted for securing these 
duties. An addition of one halfpenny per 
mile, or three-pence per day, for each horse 
riding post, was imposed in 1785, by stat. 25 
Geo. III. c. 51. The duty is secured by 
obiiging every letter of horses to deliver to 
the person hiring them a ticket, expressing 
the number of horses hired, and either the 
distance in miles to be travelled, or that the 
horses are hired by the day, as the case hap- 
pens tt> be. These tickets must be delivered 
to the bar-keeper at the first turnpike through 
which the traveller passes; and the turnpike- 
keeper gives, if demanded, what is termed an 
exchange ticket, to be produced at the next 
turnpike. The stamp-office issues to the per- 
son licenced to let post horses such a number 
of these tickets as is required, and these must 
be regularly accounted for by the person to 
whom they are issued. As an effectual check 
upon his account, the turnpike-keeper is 
obliged to return back to the stamp-office all 
the tickets he takes up from travellers. Eva- 
sions are by these means rendered difficult to 
be practised without running a great risk of 
detection. In 1787, for the more effectually 
levying the post-horse duties, a law was passed 
P O S 48$ 
authorising the commissioners of the stamp- 
office to let them to farm by public auction, 
for a sum not less than the produce in the 
year ending 1st August 1786. 
In the advertisement published by the 
commissioners in consequence ot this law, 
previous to the receiving proposals for farm- 
ing them, the total amount of the duty tor 
Great Britain is stated to have been, at the 
period above referred to, 1 19,873/. The sum 
for which, that duty was farmed in 1794, 
amouted in all to 140,030/. of which the dis- 
trict of North Britain was 6000/. 
POST DISSEISIN, a writ for him that- 
having recovered land or tenements by proe- 
cipe quod reddat, upon default of reddition 
is again disseised by the former disseispr. 
POSTEA, is the return of the proceedings 
by nisi prius into the court of common picas, 
alter a verdict, and there afterwards recorded. 
Plowd. 211. 
POSTEBN, in fortification, is a small 
gate generally made in the angle of the flank 
of a bastion, or in that of the curtin, or near 
the orillon, descending into the ditch; by 
which the garrison may march in and out un- 
perceived by the enemy, either to relieve the 
works, or to make private saliies, &c. 
POSTULATE, in mathematics, &c., is 
described to be such an easy, and self-evident 
supposition, as needs no explication or illus- 
tration to render it intelligible; as, that a 
right line may be drawn from one point to 
another. 
POTAMOGETON, pond-zveed , a genus 
of the tetrandria tetragynia class of plants, 
the corolla whereof consists of four roundish 
obtuse, hollow, patent, and unguiculated pe- 
tals: there is no pericarpium; the seeds are 
four in number, roundish and aecumi nated, gib- 
bous on one side, and compressed and angu- 
lated on the other. I bis plant has a reiri- 
gerating virtue, and is recommended in the 
cure of old ulcers. There are 14 species. 
POTASS. If a sufficient quantity of wood 
is burnt to ashes, and these ashes afterwards 
washed repeatedly with water till it comes oil 
free from any taste, and if this liquidis filtrated 
and evaporated to dryness, the substance 
which remains behind is potass ; not, how- 
ever, in a state of purity, lor it is contami- 
nated with several other substances, but suffi- 
ciently pure to exhibit many of its properties. 
In this state it occurs in commerce under the 
name of potash. When heated to redness, 
many of its impurities are burnt off’; it be- 
comes much whiter than before, and is then 
known in commerce by the name of pearl-ask. 
Still, however, it is contaminated with many 
foreign bodies, and is itself combined with 
carbonic acid gas, which blunts all its pro- 
perties. It may be obtained perfectly pure 
by the following process : 
1. Mix it with twice its weight of quick- 
lime, and ten times its weight of pure w ater. 
Boii the mixture for some hours in a clean 
iron vessel, or allow it to remain for 48 hours 
in a close glass vessel, shaking it occasionally. 
Then pass it through a filter. Boil the liquid 
obtained in a silver vessel very rapidly, till it 
is so much concentrated as to assume when 
cold the consistence of honey. Then pour 
upon it a quantity of alcohol equal in w eight 
to one-third of the pearl-ash employed. Shake 
the mixture, put it on the fire, let it boil for 
a minute or two, th«n pour it into a glass ves* 
