48 EEPOKT OF TIIE SECRETARY. 



thought. Among the communications are many which relate to supposed 

 scientific discoveries and proposed new theories of the physical phenom- 

 ena of the universe. 



There exists, especially in this country, in which there is a greater 

 amouut of popular diffusion of scientific knowledge than in auy other, 

 a class of persons who, without previous scientific training, attempt to 

 solve the most difficult problems of general physics. Among these are 

 men of considerable literary culture and much general reading, but 

 wanting in the special kind of logical and mathematical training neces- 

 sary for successful scientific investigation, they dissipate a large amount 

 of mental energy in unproductive speculations. The correspondence 

 with this class of persons is not only very onerous, but difficult to man- 

 age, inasmuch as the rejection of their propositions is generally attrib- 

 uted to prejudice or a kind of scientific oligarchy. The general 

 method which has been adopted for dealing with them is to insist 

 upon their deducing from their hypotheses some new results which 

 can be immediately verified by experiment and observation, as a test 

 of the value of their speculations. This demand is made on the ground 

 that any hypothesis of value must not only explain what is already 

 known, but must also lead to results which have not previously been 

 observed. 



Another class of correspondents write for information as to scientific 

 principles on which to found inventions for special purposes. Among 

 this class we have had within the last few years a large number of gentle 

 men of intelligence in the Southern States, who seek to retrieve fortunes 

 lost in the war by inventions which may become remunerative through 

 the sale of privileges for using them. Unfortunately, in most cases the 

 problems they essay are of too expensive a character to be brought to 

 the test of experience without the outlay of a large amount of money, 

 and frequently of too indefinite a conception to warrant success even 

 under the most favorable circumstances. The most remunerative inven- 

 tions are those of very simple character, and of general use, such as a 

 sewing-machine, rather than a steam-engine. 



Another class of correspondents consists of those who ask for the 

 information as to minerals, plants, and other objects of natural history. 

 In the answers to these the Institution has done great service in the as- 

 sistance of students, and in the diffusion, unostentatiously, of a large 

 amount of knowledge. 



In carrying on the correspondence and other parts of the general 

 operations of the establishment, much assistance has been rendered by 

 the collaborators of the Institution, among whom, during the past year, 

 our thanks are due to Prof. S. Newcomb, Prof. W. Harkness, and Prof. 

 Asaph Hall, of the Naval Observatory ; Prof. J. E. Hilgard, 0. A. Schott, 

 and Prof. William Ferrel, of the Coast Survey; Dr. Woodward and Dr. 

 Otis, of the Army Medical Museum ; Prof. J. P. Lesley and W. E. 

 Dubois, of Philadelphia; Prof. W. D. Whitney and Prof. J. D. Dana, 



