186 



SCIENCE 



[N. S. Vol. XLIII. No. 1102 



enee tlian did all the generations preceding 

 him. 



Observations made with our unaided 

 senses limit us to the most superficial as- 

 pects of natural phenomena; but when we 

 bring scientific instruments to our aid, we 

 throw off these limitations. Not only are 

 we enabled to observe more accurately and 

 more systematically all that our senses 

 ordinarily perceive, but we become endowed 

 with new senses that open up fields of 

 knowledge of which otherwise we could not 

 even have dreamed. This broadened vi- 

 sion constantly brings to light new prob- 

 lems for solution, necessitating new meth- 

 ods and greater refinement. 



The greater the advancement in any 

 branch of science, the greater must be the 

 development of the apparatus that is em- 

 ployed. The two are necessarily interde- 

 pendent. The instrument is to a great ex- 

 tent an index of the state of the science. 

 The greater the precision with which we 

 can make our observations and measure- 

 ments, the surer we are of keeping on the 

 right path in our interpretation of the 

 phenomena concerned. 



I desire to lay some emphasis on this 

 close relationship that exists between the 

 evolution of our ideas and the develop- 

 ment of instruments used in science, and I 

 wish to make some suggestions as to how 

 greater efficiency in our work may be at- 

 tained. 



My first purpose will be accomplished 

 by some citations from the history of our 

 science. Let us first recall some simple 

 cases in optics. 



Converging lenses are said to have been 

 found in the ruins of Nineveh and must 

 have been made long before the manufac- 

 ture of glass. They were certainly used at 

 an early date by the Greeks. But the dis- 

 covery of the combination to form a tele- 

 scope was not made until 1608 ; and Galileo 



soon after constructed telescopes magnify- 

 ing 30 diameters, which at once led him to 

 important discoveries. The compound 

 microscope originated at about the same 

 time. Without achromatic lenses, both of 

 these instruments were very imperfect. 

 The possibility of making an achromatic 

 lens occurred to Newton, but reliance on a 

 single unfortunate experiment led him to 

 discard the idea. The construction of such 

 lenses by Dollond, in 1757, marks the be- 

 ginning of a great epoch in the develop- 

 ment of optical instruments. It is only 

 necessary to mention the gradual develop- 

 ment of various combinations of lenses to 

 bring to mind a great array of most im- 

 portant discoveries which they have made 

 possible, not only in physics, but also in 

 astronomy, in biology, in medicine, and in 

 every natural science. 



The pin-hole camera, which led to the 

 idea of photography, was devised in the 

 second half of the sixteenth century. After 

 the image was rectified by means of a 

 mirror and its sharpness and brightness 

 increased by substituting a lens for the 

 pin-hole, this was used quite generally by 

 landscape painters. What flight of imagi- 

 nation to believe that that observed image 

 could ever paint itself! If the idea oc- 

 curred to some it was brushed aside as a 

 fancy and a dream. Such an accomplish- 

 ment must forever be beyond the reach of 

 man! No manipulation of machinery 

 could bring about such a marvel. No 

 known forces of nature could be employed. 

 But, as often happens, means were soon 

 found, and what had been considered im- 

 possible was realized. 



Even before the discovery of the camera 

 obscura the alchemist Fabricius (1556). 

 made silver chloride, and observed that 

 light blackened it. He found that an 

 image of an object imprinted itself upon 

 it. This had no significance to him, how- 



