ProK De Morgan on Anharmonic Ratio. 165 



cloud. It is extremely difficult to connect the stroke with the 

 discharge at 2^ 5"* P.M. ; although the concurrent testimony 

 of the witnesses would lead to the high probability that such 

 was the case, especially as one stated that it occurred some 

 considerable time previous to the hail that fell. The general 

 impression in the neighbourhood appears to have been, that 

 the lightning shot or glanced over the houses to the north of 

 West Street, when it struck the corner, and did not descend 

 perpendicularly from a considerable height. The discharge 

 at 2'* 5™ P.M. was, as we have already observed, precededby a 

 gush of heavy rain ; and taking the suggestion in the report 

 alluded to above into consideration, there appears to be great 

 probability that the formation of the lightning was in accord- 

 ance therewith. For upwards of half an hour violent me- 

 teorological action had taken place, the precipitation of rain 

 being very prominent. There can be no question that this 

 precipitation was accompanied by well-marked electrical phae- 

 nomena ; and when, as at 2^ 5™ p.m., an increased but sudden 

 precipitation occurred, it is likely that an agglomeration of 

 the smaller drops took place, increasing, as suggested, the 

 electric tension to such an enormous extent, that a flash 

 escaped /« the immediate neighbourhood of the houses struck; and 

 when we consider that at the time several millions of drops 

 must have been falling, each contributing its quota to the 

 general result, it is not to be wondered at that the tension of 

 the electricity was so great as to produce the very violent 

 effects witnessed. 



Bethnal Green, August 4, 1849. 



G 



XXIII. On Anharmo7iic Ratio, i^/ Professor De Morgan*. 



EOMETRICAL communications to scientific journals 

 are not so common as they used to be, which may partly 

 be attributed to the expense of woodcuts, and partly to the 

 decline of taste for geometry. The latter is accelerated by the 

 paucity of geometrical reading arising from the former cause: 

 and its effect upon soundness of mathematical habits is deadly. 

 But there is no reason why the expense of woodcuts should 

 place any obstacle in the way. I am satisfied, from sufficient 

 trial, that when proper description of the diagram is given in 

 the text, the person who draws his own diagram from the text 

 will arrive at the author's meaning in half the time which is 

 employed by another, to whom the successive appearance of 

 the parts is prevented by his seeing the whole from the be- 



* Communicated by the Author. 



