and Description of the Eidograph. 423 
replied, that the nature of the thing was such, that accuracy en- 
sued infallibly, and as it were spontaneously : so that it was im- 
possible to err without design. I inquired whether the effect 
was wrought by the drawing of lines, or by the help of a mate- 
rial instrument ? Here he began to hesitate, and to speak eva- 
sively, avoiding a clear answer, and hiding.a thing, dark and unin- 
telligible in itself; im obscure language. This alone he admitted, 
that the thing was done by the help of compasses depending 
upon a firm centre. I asked him to shew me these compasses : 
he refused, upon the plea that whoever saw them would at once 
comprehend the whole mystery. At length I earnestly entreat- 
ed that he would make a disclosure to me under the seal of se- 
crecy, and a pledge of keeping silence, promising to reveal it to 
none without his knowledge or against his will; to all which he 
gave around denial. Seeing that I talked to one deaf to im- 
portunity, I changed my style ; telling him that I trusted to dis- 
cover the thing by the blessing of God, who would, according to 
my desire, communicate the invention to me in his own good 
time, while he might chafe and fret in vain. He laughed at my 
threats, saying, that the invention surpassed the power even of 
the Devil himself! These things happened in the beginning of 
the year 1603, at which period, turning my attention to the in- 
vestigation, I laboured with all my might. TI tried the thing at 
first with a cord, which I imagined fixed at one end (for I form- 
ed the whole in my mind only, and in thought, until I had at- 
tained a true knowledge, along with a clear demonstration) ; then 
taking the other end in my fingers, I moved it round on imagi- 
nary paper, there being upon it two small spheres acting as cur- 
sors, to mark out points and proportional lines. These, indeed, 
I saw, might be formed about a fixed centre ; but then, neither 
was there any motion to or from the centre by means of the 
flexible thread, nor did the cursors change their positions upon 
it, which yet was necessary to increase or diminish the motion 
proportionally. Dismissing, therefore, lines formed by threads, 
