184* Description of an Electro-motive Engine, 



tained by this arrangement. I have no doubt, that a single 

 magnet, with the same quantity of iron as in both, would be 

 much superior to the combination alluded to. With a bar of 

 iron one foot square, the stroke would probably be sufficient 

 to work on a crank, if such should be preferred to the con- 

 trivance described. But I think the latter will always be 

 preferred for electro-magnetic engines, when the stroke is 

 several times repeated for one revolution of the fly-wheel. 

 I have tried a screw paddle worked by the axle, which ap- 

 peared to answer remarkably well. 



As the poles are never changed in this arrangement, perma- 

 nent steel magnets answer very well, the galvanic current being 

 passed only through the keeper. It is a matter of economy 

 and convenience. But it is probable, that as electro- magnets 

 are much more powerful, they will always be preferred . 



The galvanic arrangement employed, is the constant battery 

 of Daniel. The zinc plates (10 inches by 5) are placed in 

 thin leather cases, which are disposed as usual between plates 

 of copper. All the zincs 3 and all the copper plates are con- 

 nected together so as to produce the effect of one pair. 



From Dr. Wight's Neilgherry Plants. 

 I .— RANUNCULACE^E . 



This is an extensive and beautiful family of plants, many 

 of which, such as the Clematis, Ranunculus, Anemone and 

 Larkspur, rank among the most admired favourites of the 

 flower garden and arbour. Its species abound in extra-tro- 

 pical countries, but are of such rare occurrence within the 

 Tropics that, so far as I yet know, there are not above 12 or 

 14 found, truly indigenous, in the whole of the Indian penin- 

 sula, the flora of which amounts to probably not fewer than 

 5,000 species of flowering plants, of all descriptions, or it 

 stands in the ratio of about 1 to every 400 species found 



