Observations on Monochromatic Light. 143 



5' 



unfortunately the mistake, of attributing the invention of the 

 experiment to Mr Van Bemmelen, all the other editors of 

 scientific journals followed in the same track, and Dr Van 

 Marum has a fair chance of being deprived of the credit of an 

 invention, which he made fully thirty-seven years ago, and of 

 which accounts were printed in the most popular French and 

 German scientific periodicals of the time. My venerable and 

 much respected friend feels justly vexed at this, and I trust to 

 your love of truth and justice the care of setting the public right 

 on this subject. — Yours very sincerely, 



G. Moll. 



Art. X VI. — Remarks on Dr Goring 1 * Observations on the use 

 of '' Monochromatic Light with the Microscope. 



The value of practical science, and the superiority of the re- 

 sults of accurate experiments to the deductions of theory, are 

 universally acknowledged, and by none more readily than those 

 who are principally occupied with abstract research. When 

 the calculated results of general laws are found in direct oppo- 

 sition to those of accurate observation, the philosopher is on 

 the eve of some important discovery ; but whenever such an 

 opposition presents itself, he will be careful to repeat his ex- 

 periments, and he will not venture either to assail the correct- 

 ness of a well established and universally admitted law, or to 

 seek for the new principle on which the discrepancy depends, 

 till these experiments are placed beyond a doubt. While we 

 admit, therefore, the transcendent value of practical science, 

 we must so far take the part of theory as to insist upon a ri- 

 gorous scrutiny of the facts by which it is opposed. 



As I was the first person who recommended the use of ar- 

 tificial monochromatic light for microscopical observations, by 

 arguments drawn not only from theory but from immediate and 

 frequently repeated observations, and as Dr Goring's observa- 

 tions, as recorded in a preceding article, are, if correct, entirely 

 subversive of mine, it is necessary that I should relieve science 

 from the opprobrium of these contending opinions. As Dr 



