49 
& then you need to fferae no Scott, 
whether you sayle by day or by night ; 
& to-morrow by 7 of the clocke 
you shall meete with Sir Andrew Barton, Knight. 
The Percy Folio is probably not earlier than the black- 
letter copies of the ballad, but the text is altogether freer 
from corruptions. No existing copy of Sir Andrew Barton 
can claim to be older than the seventeenth century. The 
possibility of using the flashing of a mirror to obtain infor- 
mation from a distance is shown in the following extract 
from a book of popular science of the seventeenth century : 
“ If there be never so dark a room with a door or window 
open, take a looking-glass in your hand, and hold it against 
the sun, at a great distance from the door or window, and 
moving the glass up and down, till the reflections of the 
sun be upon your object, and then you may perfectly behold 
anything in the room, or see to read a letter. Some un- 
happy boys used to dazzle people’s eyes with a glass in this 
order, as they walk the streets.” — This extract is from a 
work entitled “A Rich Cabinet with variety of Inventions.” 
My copy of this work is destitute of title, but it was printed 
about 1670 — 80. 
The “Speculum Topographicum, or the Topographicall 
Glasse,” was “newly set forth by Arthur Hopton, gentleman,” 
and “Printed at London by N. O. for Simon Waterson, 
dwelling at the signe of the Crowne in Paules Churchyard, 
1611.” At p. 183 we read the following: “To make a 
glasse whereby to discerne any small thing, as to reade a 
written letter a quarter or halfe a mile off. We have an 
imitation of such glasses as these about London commonly 
to bee sold, but they be so small that they stand one in 
small steede, but amongst the writers of perspective, I have 
read that if you take a glasse of the same mettall that 
burning glasses be, and 16 or 17 inches broad, whose center 
place directly against ye object you looke vpon, and let it not 
