Mr. S. Sharpe on the Figure of the Cells of the Honeycomb, 19 



nitude. Being of a more durable nature than the granite, it 

 has been much less affected by the weather ; and while the 

 granite in its vicinity has been worn down, and in a great 

 measure levelled, it has remained in the form of a ridge. In 

 several places the quartz is intermixed with felspar, which 

 makes it more liable to be acted on by the weather ; and ac- 

 cordingly we find that in these places it is worn down, and the 

 continuity of the ridge is thus interrupted. 



25. From a trap vein which extends from the cantonment 

 of Secunderabad in a westerly direction. When it approaches 

 the quartz vein described above, it divides into two or three 

 branches, and penetrates the quartz in several places. 



26. Red granite without mica, from the vicinity of the quartz. 



27. Quartz and felspar in large concretions, from the vicinity 

 of the quartz. 



28. Granite with epidotic veins, associated with the quartz, 

 near the place where it is penetrated by the trap. 



29. 30. Granite without mica found near the quartz. 



31. Disintegrated granite from a depth of four or five feet 

 from below the soil, beginning to consolidate. 



32. From immediately under the soil. 



33. Nodular basalt from a trap vein. 



34. Nodules of trap found loose on the surface of the ground. 



VI. On the Figure of the Cells of the Honeycomb. By 



Samuel Sharpe, Esq. F.G.S.* 

 T> EAUMUR mentions, in his History of Insects, vol. v. 

 ■"• p. 39, that he employed Maraldi to measure a cell of a 

 bee's honeycomb, and Kcenig to calculate what the propor- 

 tions of the three*sided pyramid at the end should be, in order 

 that the whole cell might be made with the least materials ; it 

 being easily shown that the contents of the cell would be the 

 same, whatever the height of the three-sided pyramid, even 

 if = o, in which case the prism would have a plain end. 



Their reports nearly agreed ; but the difference still is not 

 to be overlooked, as will be seen in the angles of the parallelo- 

 grams of the pyramid : 



Maraldi's measurement 109° 28' and 70° 32' 



Kcenig's calculation 109 26 Vo 34 



And neither naturalists nor mathematicians have accounted 

 for the difference. 



As, from the nature of the materials, the angles can hardly 

 be measured by reflection from the sides with a reflective go- 

 niometer, we have no better means of measuring than Maraldi 

 * Communicated bv the Author. 



D2 had, 



