274 M E M O I R S of the 
which afterwards became as bright as the former ^ he obferved 
the points F and G to arife, and the arch F G gradually to 
contra(fl:, till at length the two arches FHG, and FG became 
coincident 3 when, for a great Ipace, the fecondary Iris loft 
its colours, and appeared like a white arch at the top, he alfb 
obferved, that at the points F and G, the interfeftion of the 
interior red of the fecondary /m, and the exterior red of the 
arch was much more intenfely red than the outward limb of 
the primary 7m; and that during the whole appearance, the 
upper part of the third Iris was not at all vifible beyond the 
interfe£lions FG: This uncommon fight continued for about 
2 minutes. Mr. Halky was at firft amazed therewith, but 
afterwards recollecting that the fun fhone along the river 2)66, 
which from thence empties itfelf W. N. W. where the fun 
then was, he concluded that this fecondary arch AFHGC 
was produced by the beams of the fun refle6led from the 
water, which at that time was very calm, and it had been 
much more bright, had it been then high, as it was low-water, 
when all the lands were bare. 
^ Roman Shield 5 by Mr. Thoresby. Phil. Tranf. K" 241 
p. 205. 
THE ancient Romans had three words, viz. Scutum^ 
__ ^arma^ and Clypeus^ to exprefs that defenfive weapon 
we generally call in Englijb a fhield, which, notwithftanding 
their different forms or matter, their authors, efpecially in the 
declenfion of the empire, frequently confound, as probably we 
now do fhield, buckler, and target: Of thele fhields or buck- 
lers, Mr. Thoresby had one, fee Fig. 2. Plate IX. of the 
\Parma kind, rightly fo called, quod e medio in cmnes partes 
fa par J whereas the Scutum vj^s moflly oval, tho' Ibmetimes 
imbricated, with corners equally broad 3 it is 1 5 inches dia- 
meter, whereof a little more than a third part was pofTefled by 
the UrnbOy or protuberant bofs, which is made of an even con- 
vex plate, wrought hollow on the infide to receive the gladia- 
tor's handj on the centre of this is a fmaller bofs, wherein 
there feems to have been fixed iome kind of CufpiSy or iharp 
offenfive weapon; from the faid Umbo^ the fhield is four 
inches and a half broad on each (ide, in which are eleven cir- 
cular cquidiftant rows of brafs fluds of that fize, that 222 are 
fet in the outmoft circle, which is four foot, wanting three 
inches, the circumference of the buckler; the inmoft circle is 
placed upon the Umbo itfelf, the next 8 upon as many circular 
plate« 
