PREFACE. vii 



the present high price of coals had been already reached, I 

 may yet claim to have anticipated the recent check to the 

 process of exhaustion, since similar views were indicated 

 in a paper specially devoted to that portion of the subject, 

 which appeared in the St. Pauls Magazine for November 

 1871, and forms one of the essays in the second edition of 

 the first series of my ' Light Science for Leisure Hours.' 



Some of the anticipations in the essay on Flying 

 Machines have been realised since the essay was written 

 by the construction of aerial instruments depending for 

 their support on the rapid motion of plane surfaces. 



A singular illustration of the mischievous effects which 

 may result from foolish superstitions, such as are dealt with 

 in the essay on that subject, was afforded very recently. 

 The ship Adela, loaded with stores for our countrymen 

 engaged in the Ashantee war, and ready to start on Friday, 

 September 19, was delayed (according to the Daily News) 

 in consequence of the sailors' unwillingness to start on a 

 Friday. 



RICHARD A. PROCTOR. 



LONDON: October 1873. 



