RIO 
yellow, green, blue, indigo, and violet, in 
order, are one to another as the cube roots 
of the squares of the eight lengths of a chord, 
which sound the notes in an octave, sol, la, 
fa, sol, la, mi, fa, sol ; that is, as the cube 
roots of the squares of the numbers 1, 
l> i 5 - These rings appeared of 
that prismatic colour, with which they were 
illuminated, and by projecting the prismatic 
colours immediately upon the glasses, he 
found that the light, which fell on tl’o dark 
spaces between the coloured rings, was 
transmitted through the glasses without any 
change of colour. From this circumstance 
he thought that the origin of these rings is 
manifest ; because the air between the 
glasses is disposed according to its various 
thickness, in some places to reflect, and in 
others to transmit the light of any particu- 
lar colour, and in the same place to reflect 
that of one colour, where it transmits that 
of another. 
In examining the phenomena of colours 
made by a denser medium surrounded by a 
rarer, such as those which appear in plates 
of Muscovy glass, bubbles of soap and 
water, &c. the colours were found to be 
much more vivid than the others, which were 
made with a rarer medium surrounded by a 
denser. From the preceding phenomena 
it is an obvious deduction, that the transpa- 
rent parts of bodies, according to their se- 
veral series, reflect rays of one colour and 
transmit those of another ; on the samfe ac- 
count that thin plates, or bubbles, reflect or 
transmit those rays ; and this Sir Isaac 
Newton supposed to be the reason of all 
their colours. Another inference is, that 
the particles even of those bodies which we 
call opaque are in reality transparent, which 
persons who are in the habit of using the 
microscope must continually perceive. See 
Newton’s Optics: see also Colour, &c. 
RIOT, rout, and unlawful assembly. 
When three persons, or more, assemble 
themselves together, with an intent mu- 
tually to assist one another, against any 
who shall oppose them in the execution of 
some enterprise of a private nature, with 
force or violence, against the peace, or to 
the manifest terror of the people, whether 
the act intended were of itself lawful or un- 
lawful ; if they only meet for such a pur- 
pose or intent, though they shall after de- 
part of their own accord without doing any 
thing, this is an uidawful assembly. By 
34 Edward III. c. 1, it is enacted, that if a 
justice find persons riotously assembled, he 
RIS 
alone has not only power to arrest the of- 
fenders, and bind them to their good beha- 
viour, or imprison them if they do not olfer 
good bail ; but he may also authorise others 
to arrest them, by a bare verbal command, 
without other warrant ; and by force there- 
of, the persons so commanded may pursue 
and arrest tlie offenders in his absence, as 
well as presence. It is also said, that after 
any riot is over, any one justice may send 
his warrant to arrest any person who was 
concerned in it, and that he may send him 
to gaol till he shall find sureties for his good 
behaviour. The punishment of unlawful 
assemblies, if to the ntimber of twelve, may 
be capital; according to the circumstances 
which attend them ; but from the number 
of three to eleven, it is by fine and imprison- 
ment only. The same is the case in riots 
and routs by the common law, to which the 
pillory, in very enormous cases, has been 
sometimes superadded. 
By the act 1 George II. st. 2, c. 5, every 
justice, mayor, sheriff, &c. shall, upon no- 
tice of a riot, or unlawful, tumultuous as- 
sembly of twelve persons, proceed to the 
place, and make proclamation for them to 
depart, upon the pains of that act com- 
monly called the riot-act. If any person 
shall wilfully oppose or hurt any person go- 
ing to make proclamation, and prevent the 
same, he shall be guilty of felony, without 
benefit of clergy. If twelve continue toge- 
ther after proclamation, for one hour, it is 
felony, in like manner. And every justice, 
&c. shall apprehend persons, and if the 
rioters are killed, the justice, &c. shall not 
answer for it. A riot, though of fewer per- 
sons than twelve, to destroy any church, 
chapel, meeting,, or dwelling-house, out- 
house, &c. is a capital felony : and the hun- 
dred shall answer the damages, as in case 
of robbery. 
If two justices go out to quell a riot, they 
may assemble the posse comitatus, and every 
person capable of travelling is, upon being 
warned, to join them, on pain of imprison- 
ment. 13 Henry IV. c. 7, ts. 1, 2, 11 , 5. 
c. 8, s. 2. 
RISBAN, in fortification, a flat piece of 
ground upon which a fort is constructed for 
the defence and security of a port or har- 
bour. It likewise means the fort itself. 
The famous Risban, of Dunkirk, was built 
entirely of brick and stone ; having within 
its walls excellent barracks, a large cistern 
well supplied with water, magazines for 
stores, provisions, and ammunition, A ready 
