all known Substances to the Magnetic Influence, i§t. 131 



And by such a code it would be perfectly easy for the con- 

 ductor of the experiment to give every requisite direction for 

 the application of the magnets, at any distance to which the 

 blows could be distinctly heard. 



At distances, however, beyond the limits of communicable 

 vibrations, the application of the magnets must be by precon- 

 certed arrangement. In this case a certain moment of time 

 might be agreed upon for the application of the magnets ; and 

 given intervals arranged when the magnets should be reversed, 

 and when neutrahzed. 



Though, in the preceding investigations, the equal permeabi- 

 lity of solid substances generally has been verified or assumed, 

 nothing has yet been stated in respect to the effect of the inter- 

 position of metallic iron on the action of the magnet. This sub- 

 stance, the action of which on the magnetic needle is so peculiar, 

 has indeed been made the subject of very particular and diligent 

 investigation, but the results have been intentionally omitted, 

 both because these results are somewhat different from all the 

 others, and because iron, in a metallic state, is not hkely to be 

 met with in mining, so as in any way to affect the universality of 

 application of the process herein suggested for the measurement 

 of distances otherwise indeterminable. 



Thus much, however, may be briefly mentioned, that iron, in 

 any state in which it can be had, whether malleable or cast, whe- 



4, 1. Is the magnet against wall ? 4, 1. It is against the wall. 



4, 2. Is the magnet neutralized ? 4, 2. It is neutralized. 



4. 3. Yes ! 4, 3. Yes. It is. 



4. 4. No ! 4, 4. No. It is not. 



1, 2, 1. Lay aside the magnet till di- 1, 2, 1. May we lay aside the mag- 



rected. net ? 



1, 2, 2. Place the magnet. 1, 2, 2. Shall we place the magnet ? 



1, 2, 3. Which pole of the magnet is 1, 2, 3. The North pole is presented. 



l)resented ? 2, 1, 2. The South pole is presented. 



2, 1, 3. Where is the magnet placed ? Answer by signal of other column. 



ADDITIONAL SIGNALS TO BE FILLED UP. 



2, 2, 1 ; 2, 2, 2; 2, 2, 3; 2, 3, 1 ; 2, 3, 2 ; 2, 3, 3; 3, 1, 2; 3, 2, 2; 3, 2,3; 

 3,3,1; 3,3,2; 3,3,3; &c. 



N. B. The separation of the number of blows by a comma, denotes a sen- 

 sible pause between each series. 



l2 



