Pee", | 
XXXVI. 
THE AUTOMATIC IMAGE-FINDER. By THE REV. RICHARD 
C. BODKIN. 
[Read NovemBer 21, 1894; Received for Publication Novemprr 23, 1894; 
Published January 21, 1895. ] 
1°.— Construction of the Instrument, and the Principles 
upon which it is based. 
THe instrument which I have the honour of bringing under 
the notice of the Royal Dublin Society is called the Automatic 
Image-Finder. This name but very inadequately expresses the 
end and scope of the instrument ; still I could find no better. 
The real object I had in designing and constructing the 
instrument is threefold :— 
1. To show where the image of any object placed before any 
lens must be formed ; 
2. To prove that the image is found there; and 
3. To help to explain the construction of the various optical 
instruments in use, such as the microscope, telescope, 
camera, and projection lamp. 
Thus the Automatic Image-Finder is essentially a teaching 
instrument. 
The construction of this instrument is very simple, and depends 
on a few elementary principles. 
1. It is well known that the image of an object is invariably 
seen where the rays proceeding from that object meet, or seem to 
meet, ¢.g. if the rays meet at A (fig. 1), we see the image at 
A; if they meet at a we see the image at a; and if they do 
not meet at all, but merely seem to meet at a’, then we see the 
image at a’. 
2. The rays proceeding from any point in an object always 
meet (or, if not, at least seem to meet) at some point or other alony 
SCIEN. PROC. R.D.S., VOL. VIII., PART IV. Y 
