!58 



Notes and Correspondence. 



[April, 



in those parts of the earth's surface 

 towards the equator. North of the 

 Line, then, this westerly direction 

 of the wind, combined with the 

 southerly direction spoken of before, 

 gives, (by the well-known mechani- 

 cal principle of the parallelogram of 

 forces,) as a resultant, a direction of 

 the wind from the N.E., this is the 

 trade -wind of the North Atlantic. 

 But next, let it be observed, this 

 •wind owes almost all its force to the 

 fact of the enormous radiation of 

 heat from the surface of the Sahara, 

 causing a prodigious rarefaction in 

 the atmosphere above it — hence a 

 vehement impetus is given to the 

 current of air traversing it from the 

 N.E. ; that is to say to the wind, 

 which, as we have seen by its action 

 on the waters of the Atlantic, is the 

 main cause of the Gulf Stream. 



Suppose, then, the Sahara to be an 

 expanse, not of sand, as now ; but, 

 as formerly, of water ; what would 

 be the results ? 



Much that of the old nursery 

 story — "Water won't quench fire, 

 fire won't burn stick," &c. — the 

 trade-wind would cease, or be so re- 

 duced in strength as to exert but 



slight pressure on the surface of the 

 Atlantic ; then, as a consequence, the 

 Gulf Stream would either cease or 

 shrink into insignificant dimensions ; 

 the icebergs from Greenland, instead 

 of being melted by the heated waters 

 far towards the north, would en- 

 croach more and more southwards ; 

 the seas round our own islands, and 

 (a fortiori) those more to the north, 

 would again present the spectacle of 

 an Arctic or sub- Arctic climate, at 

 least as severe as that of Labrador in 

 the same latitude : in short, 



" grave rediret 



Sseculum," 



the phenomena of the Glacial 

 Epoch would be renewed over the 

 greater part of temperate Europe. 

 My letter is longer than I had in- 

 tended it to be, though I have rather 

 indicated than expressed many 

 points of my reasoning, and have 

 strictly avoided all collateral issues. 

 May I venture to hope that some 

 abler pen will take these up, and 

 thoroughly ventilate the whole sub- 

 ject. 



H. J. Ward. 



Bridgnorth, 11th March, 1865. 



Tlie New South Wales Coal Fields. From Mr. John Mackenzie, Government 

 Examiner of Coal Fields, New South Wales.* 



Since I last wrote to you, and 

 within six weeks, I have had two 

 long and tedious exploring journeys. 

 In the first trip, I rode in about 

 ten days upwards of 300 miles over 

 a very rugged country, going in 

 one place over a barren sandstone 

 country thirty-five miles in length. 

 I left here with my man and three 

 horses, one horse being the pack 

 horse — that is, it carried the pro- 



* This communication reaches us 

 through the courtesy of a correspon- 

 dent in England, to whom it is ad- 

 dressed (not to the Editors). Our 

 readers will, we believe, be glad at all 

 times to peruse similar authentic re- 

 cords of the progress of scientific dis- 

 covery abroad. — The Editors. 



visions, panakins, blankets, pick, 

 saddle-bag, &c, and a piece of oil- 

 skin, with some calico stuffed with 

 sea-weed for me to lie upon. I 

 went for the purpose of seeing 

 whether the Hartley coal seams in 

 the county of Cork belonged to 

 the same coal basin as Newcastle 

 and Wollongong (see plan of New 

 South Wales), and to see if I could 

 find out with which known seams 

 of coal on this side they were 

 identical. I was able to recognize 

 them. Another reason for my 

 going was, that I had an idea that 

 I could find coal identical with the 

 Fitzroy coal at a distance of thirty 

 miles from Sydney (the metropolis 

 of New South Wales). The route 



