Opticks 1717 - Up

I 200
plain the Inore compounded. And firff to fhew
ho& the Colours in .the fourth and, eighteenth
Obfervations are produced, let there be taken
in any right Line from the .Point Y, [in Fig. 6.1
the lerlgths Y A,, 5% YC, YD, \‘JL yJ$ YG,
UH, in proportion to one another, ZIS the Cube
Roots of the Squares of the Numbers:, 4, A, $
I i I II
T? T> 7) 57 I, whereby the lengths of a mu&al
Chord to found all. the Notes in an eighth. ai+e
repreknted ; that is,’ in the proportion of the
Numbers 6300, 68x4, 7114, 7631, ~W’, 8855,
3_2+3, 10000. end at the Points A, J3, C, Q
E:, IT9 G, J-J, let perpendiculars Act, JS P, Ws’c, be
u&k1 7 by tv~lloii! Jntervals the l!~xtent of the
’ feveral CoIo~irs fkr underneath againit them, is
t,o be reprefcnted. Then :divide the Lisle A..ti
in fuch proportion as the Numbers I, 3 3, 5,
6, 7, y7 io, X:P, @c. kc at the Points of Diviiibn,
denote. And through thofe Diviiions from 31
draw Lines I I, 2 K, 3 L, 5 .IB/II, 6N, 70, 62.
NQ+LV if A. 7, bc ii:q3poli”d to rcprcfent the
thiclrnefs of any thin tranfparc”t kxiy, at which
the outmoi1 violet is molt copioufy refletted
in the’ fit4 Ring, or Series of’Colours, then by
the .I 3th Obfcrvation , 1-J M will, reprel’ent j,ts
thicl~ncfs, at which the .ulmofi red is moit: co1
piouflp refjle&d In the fi~mc 6erics. Alf’o by
ahc yth and r 6th Obkrvntions , A. 6 and l-3 N
will’ denote the thicknell& at which thof’e cxtrcme
Colours are mott copiouily rcfk&d in
the fecund. Series, and A 10 and HQ the thick-
~~cfCs, at whicl~ they are moit copioufly refleAcd
in the third Series, 4nd I‘0 on. .Rnd the
thickncfs at which any of the intertnedia~e Coluurs