177 



Description of an Electro-motive Engine, by Inspector Gene- 

 ral J. Macleod, of the Madras Medical Service. Com- 

 municated by Dr. F. Mouat. PI. iv. 



[Note by Dr. Mouat. — Mr. Macleod is well known in the Madras 

 Presidency, as an able and excellent practical chemist and mechanic, 

 who has devoted considerable time and attention to such subjects. The 

 ingenious instrument described, which works exceedingly well, may be 

 applied to a variety of useful purposes, and the power multiplied to 

 any extent by increasing the strength of the battery, and size as well 

 as number of the magnets. Few subjects connected with the arts have 

 recently attracted more attention than the application of electro- 

 magnetic power to supersede steam in its infinite uses and appliances. 

 One of the greatest difficulties and barriers to its success has been com- 

 pletely overcome by Mr. Macleod, whose paper we have no doubt will 

 attract considerable attention among those engaged in similar inquiries 

 in Europe] 



The discoveries made of late years in electro-magnetism, 

 more especially the extraordinary power imparted to soft iron 

 by means of the galvanic current, have given rise to various 

 ingenious attempts to apply the new agent as a motive pow- 

 er. All these attempts, however, appear to have been unsuc- 

 cessful. (See Mechanics' Magazine, January 1844, page 61.) 

 I have tried the arrangements of Devonport, Jacobi, Davidson 

 and Taylor ; and though small models or toys can be made 

 to work by either of them, I am inclined to think that it 

 could easily be explained, why they have not been found to 

 answer on the large scale. 



The space over which electro-magnets exert any consi- 

 derable power being very limited, and by far the greatest 

 portion being exerted close to the magnet, it is evident that 

 none of this last can be sacrificed without the loss of a con- 

 siderable proportion, if not the greater part, of the power, 

 together with a corresponding waste of materials. 



I do not find it stated at what distance from each other the 

 rotating and fixed magnets were placed in Devonport's and 



