1819.] Description of an improved Microscope. 57 
light, the image wants it; if distinctness or field are wanted, the 
image is likewise defective in these points. Another very great 
reformation is cutting short the amplification of the image down to 
the standard of the magnifying power of the microscope producing 
it. Thus if the microscope magnifies 60 times, the image is 
only allowed to be magnified 60 timies, and so on: this is done 
by only suffering the rays to diverge to the distance of six inches. 
By these means, the maximum of sharpness and distinctness is 
obtained, so that the image is like a miniature picture, where 
every thing is seen just as if one were looking through the glasses. 
What purpose does it serve (save that of astonishing women and 
children) to suffer the rays to diverge till you have made a flea 
as big as ajack-ass, Xc. 
Monstrum horrendum, informe, ingens, cui lumen ademptum— 
at the expense too of all light, distinctness, and every thing 
valuable in vision. My instrument shows none of these wonderful 
wonders. I hold them in supreme contempt, but in real mag= 
nifying power it is nevertheless greatly superior.* No sensible 
optician ever forces a telescope, or microscope, to a higher 
power than it is capable of bearing, as the object is not only 
seen no better (though larger), but a vast deal worse. If it is 
asked why I did not, at least, suffer the rays to diverge to eight 
inches instead of six, eight inches being the standard of sight, I 
answer, I do not believe eight inches to be the standard of sight, 
but that it is much less than that. I am not conscious that I 
am either long or short sighted. I can see to read moderately 
sized print at the distance of five feet, and I can read the same 
41 inches from my eye. When I go to look narrowly into any 
thing, I generally look at it 41 inches distance. Let any lady, 
with acknowledged good eyes, take a microscopical object, such 
as a transparent slider, or some such thing, and let her mark 
the distance she places it from her eye, when she sees it to the 
best advantage, so as to see most into its nature. I am sure 
99 out of 100 will place it nearer than eightinches. However, I 
have assumed six inches. 
As an opaque solar microscope, this instrument possesses the 
same advantages over the common one as the transparent part 
does ; it does not, however, magnify above 60 diameters (com- 
mon computation), and would, in my opinion, be of no use if it 
did. | may mention that the common transparent body will not 
tg an image of an opaque body, from its affording so little 
ight. 
As a lucernal microscope, this is likewise superior to the com- 
mon one, for which all that is necessary is to place a fountain 
lamp on the floor, on one side of the instrument, on the same 
* The real power of the glasses producing the image is about four times greater 
than that of the lenses generally used for solar microscopes. 
