THE FOKHATIOtf OF COAL. 



single splendid light of solar completeness can have it without 

 difficulty, but not so where the cost in pence per hour per 

 burner has to be counted. 



I should add that before the publication of King's specifica- 

 tion, Mr. (now Sir William) Grove proposed the use of a helix 

 or coil of platinum, made incandescent by electricity, as a light 

 to be used for certain purposes. This was shown at the Royal 

 Society on or about December 1st, 1845. 



Since the publication of the above in 1879, I have learned, 

 from a paper in the Quarterly Journal of Science, by Professor 

 Ayrton, that in 1841 an English patent was granted to De 

 Moylens for electric lighting by incandescence. 



CHAPTER XX. 



THE FORMATION OF COAL. 



IN the course of a pedestrian excursion made in the summer 

 of 1855 I came upon the Aachensee, one of the lakes of North 

 Tyrol rarely visited by tourists. It is situated about 30 miles 

 N. E. of Innspruck, and fills the basin of a deep valley, the 

 upper slopes of which are steep and richly wooded. The water 

 of this lake is remarkably transparent and colorless. With one 

 exception, that of the fountain of Cyane a deep pool forming 

 the source of the little Syracusan river it is the most trans- 

 parent body of water I remember to have seen. This trans- 

 parency revealed a very remarkable sub-aqueous landscape. 

 The bottom of the lake is strewn with branches and trunks of 

 trees, which in some parts are in almost forest-like profusion. 

 As I was alone in a rather solitary region, and carrying only a 

 satchel of luggage, my only means of further exploration were 

 those afforded by swimming and diving. Being an expert in 

 these, and the July summer day very calm and hot, I remained 

 a long time in the water, and, by swimming very carefully to 

 avoid ripples, was able to survey a considerable area of the 

 interesting scene below. 



The fact which struck me the most forcibly, and at first 

 appeared surprising, was the upright position of many of the 

 large, trunks, which are of various lengths some altogether 



