Mathematical and Physical Science. 343 



fibres. The stem being destroyed as a support, the branches 

 fell in ruinous aggregation round it. It appears that a labur- 

 num tree situated about 12 yards to the east had been twice 

 struck by lightning, first (I believe) in 1834, and again in 1844. 

 It was split, but not barked. An elm situated about 100 yards 

 to the north was struck, and in like manner split, but not 

 barked. These differences may, perhaps, be due to the dif- 

 ference of structure in the wood ; but in all cases before at- 

 tempting to explain the phenomena observed as the effects 

 of lightning, it is desirable to be informed of the times of 

 year when the trees were struck. The precise points of en- 

 trance and exit of the lightning cannot be stated. A small 

 quantity of black powder was found in the fissured part of 

 the wood, at the base of the twisted branches ; but nothing 

 was observed which could determine the course or the chemi- 

 cal effects of the electrical agent.* 



" On the Climate of the Valley of the Nile," by Mr T. S. 

 Wells. — The observations extend from the 6th of December 

 1849 to the 16th of March 1850. The instruments were 

 kept in a cabin in the boat of an invalid. The cabin was six 

 feet high, 12 feet broad, and 10 feet deep. Its floor was 

 from 1 to 2 feet above the level of the river. The dry and 

 wet bulb thermometers, and the barometer were fixed to a 

 beam in the centre of the cabin, where they were not ex- 

 posed either to the direct or reflected rays of the sun. There 

 were six glass windows to the cabin, provided with open 

 blinds. Some of these windows were always open during 

 the day, so that the morning and afternoon observations may 

 be considered to represent the temperature of the open air 

 in the shade. Sometimes a window was open until after the 

 evening observations, but more frequently this was not the 

 case, and to this I ascribe the fact that the mean of the evening 

 observations is above that of the morning. A register night 

 thermometer was fixed outside one of the windows, and the 

 lowest temperature observed each day is recorded. These 

 daily observations were made at the hours of 9 A.M., 3 P.M., 



* Since the Report was presented, Mr Wauchope has cleared a larger p.^r 

 tion of the roots, and has found them split and blackened considerably. 



