20 



tives ^rere taken, one with a and amplifier made by Wales, the other with 

 a of Powell and Lealand. Each of these gave an enlargement of more 

 than two thousand diameters. An enlarged copy of these gave them over 

 nineteen thousand diameters. The spots of the diatom thus magnified are f 

 of an inch in diameter, perfectly sharp in outline, circular in form, but ap- 

 pearing as if they were hexagonal when looked at from a distance. 



Dr. Holmes then said that at the risk of taxing the powers of belief of 

 those before him he would attempt to give some idea of what is meant by an 

 enlargement of twenty thousand diameters, within a fraction of which these 

 objects are amplified. 



It means that their surface, or that portion of it which you see, looks four 

 hundred million times as large as it really is. 



If your thumb-nail were thus magnified it would cover eighteen acres 

 of ground. 



. A fly, weighing one grain, thus magnified in surface and in like propor- 

 tion in thickness so as to keep his proper figure, if his weight increased at 

 the same rate as his bulk, would weigh as much as a million horses rolled 

 into one great monster horse. 



A man weighs a million grains, and magnified in each dimension, as 

 much as these dots are enlarged, would weigh as much as a billion horses; 

 more very probably than ever lived on this planet, from the Adam of horse- 

 flesh to the present time. 



Many who are here this evening remember the famous mcon-hoax of 

 Richard Adams Locke. It seems not impossible that the fancy of enlarging 

 telescopic images by the microscope so as to bring out details upon the sur- 

 face of the satellite may yet be realized. If the moon looks about a foot in 

 diameter, it would, if enlarged as these dots are enlarged, be extended to 

 nearly four miles in diameter, say, if you will, ^ of its actual diameter. 

 This would give us pictures of everything on the scale of one inch to fifty 

 feet, and would shew us men and women, if such there were on the moon's 

 surface, as exceedingly interesting little animals of about the size of certain 

 insects held in small esteem by the human species, and very easily seen as 

 well as felt. 



Errors excepted, of course, in the above calculations, which are believed, 

 however, to be essentially correct. 



Dr. Holmes then said that he had been particularly requested to bring 

 with him the microscope which he is in the habit of using, the mechanical 

 arrangements of which are of his own contrivance. The glasses shewn in 

 connection with it were a , a and a ^ made by Spencer. 



This instrument was shewn with the same test which had been exhibited 

 in the photographs, but magnified in it to about one thousand diameters, 

 shewing the dots by oblique illumination with the lamp and the small plano- 

 convex lens occupying one opening of the diaphragm. 



