Mr Haidinger on the Manganese Ores. 41 



Larvae, which are produced under the surface have been 

 very numerous, and the onion and cauliflower tribe have 

 suffered much. An insect, which I have not been able to de- 

 tect, has almost totally destroyed my crop of apples and 

 pears, by eating out the cores of the fruit when just set. 

 Plums are all destroyed. I do not recollect a richer display 

 of blossom than that which we had in spring, and our disap- 

 pointment has been proportional to the hope excited. The 

 Curculio vastator, which, by committing its depredations in 

 the night, too often escapes the vigilance of the gardener, 

 has not been so numerous as usual ; nor have I seen so many 

 moths and butterflies as usually occur. For some years past 

 wasps have been scarce, but this season they are plentiful. 

 I have observed that they are fond of the flower of the 

 Daucus hispidus, which seems to stupify them, as they fall to 

 the ground when the flower is shaken, or they may be picked 

 off by means of pincers. Perhaps the flower of the common 

 carrot may have the same effect. At any rate. I hope that 

 the Daucus hispidus will be found a useful means of destroy- 

 ing this arch enemy of ripe fruit, by being planted in diffe- 

 rent parts of a garden, — a boy or girl being employed to go 

 round and pick oft* the wasps that settle on the flowers. 

 Ever yours truly, 



G. S. Mackenzie. 

 Coul, 3d August 1824. 



Art. VII. — On the Crystalline Forms and Properties of the 

 Manganese Ores. By William Haidinger, Esq. F. JR. S. E. 

 Communicated by the Author. With a Plate. 



I. Prismatoidal Manganese Ore. 



Fundamental form. Scalene four-sided pyramid. P = 

 130 - 49\ 120» 54/, 80° 22'. Plate II. Fig. 1. 

 a : b : c :=1 : V 3.37 : >/ 2.4. 

 Character of combinations, hemi-prismatic, with inclined 

 faces. 



