OcTnHi:R. 1911 



KNOWLEDGE. 



405 



region. The wasteful methods of use are justified ou the 

 .ground tliat the replenishment so greatly exceeds the flow 

 that the loss of water is unimportant. After a careful 

 examination of the available evidence, Professor Gregory 

 entirely rejects the view that the wells are supplied by 

 rainfall, and are, in fact, of the normal artesian type. He 

 holds that the water is derived from three main sources : 

 (1) plutonic wafer from the interior of the earth ; (2) residual 

 water enclosed in the rocks at the time of their formation : 

 13) rainfall which percolated into the sandstones at an earlier 

 geological period. If this is the case the supply is not 

 unlimited.' as is maintained by those who support the older 

 theory, and a diminution of yield is to be expected ; so much 

 so that in the near future pumping may have to be resorted 

 to in order to keep up the supply. .-Vccording to Professor 

 Gregory, this diminution has already begun in most parts of 

 yueensland. South .Australia and Xew South Wales. 



The question is obviously of vast importance to Australia. 

 If Professor Gregorv's Views are correct, the present waste 

 is deplorable, and should be stopped as soon as possible. 

 Fortunately, if it does become necessary to resort to pumping, 

 the waste of water will be much lessened, and the decline of 

 the water-level will become correspondingly slower. 



PORPHYKITIC MONCHIOUITES IX BRITAIN.— 

 Several very typical monchiquites have now been described 

 from these islands, especially from Scotland. The monchi- 

 quites are characterised by their abundance of ferro-magnesian 

 minerals, their groundmass of analcite, and fretjuently by the 

 presence of remarkable ocelli, composed of radially arranged 

 augite prisms surrounding a nucleus of analcite. .A remark- 

 able variety has recently been described by Professor \V. S. 

 Boulton, in a communication to the Geological Society, This 

 rock is intrusive into the Old Red Sandstone of Monmouthshire, 

 between Chepstow and L'sk, and contains huge phenocrysts, 

 attaining five or six inches in size, of augite and biotite. 

 Xodules of olivine-augite rock are also described. This 

 rock is compared with the monchiquites of Colonsay and 

 Argyllshire. It is remarkably similar to a dyke-rock from 

 Kilchattan in Colonsay, which carries enormous crystals of 

 hornblende, biotite and augite. This rock, described in the 

 Summary of Progress of the Geological Survey for 1909, 

 page 52, is distinguished by containing nepheline, thus belong- 

 ing to the rare group of nepheline-monchiqnite. The writer 

 of this column has discovered a third example of porphyritic 

 monchiquite in .Ayrshire. It occurs as part of an intricate 

 complex intruding the agglomerate of a volcanic rock of Late 

 Palaeozoic ("Permian") age, at Carskeoch Hill, near Patna. 

 This rock carries huge phenocrysts of red barkevicitic horn- 

 blende, and biotite. Purple augite and olivine occur as a 

 second and smaller generation of phenocrysts in the usual 

 monchiquitic groundmass. The rock forms part of a complex 

 in which, teschenite, teschenite-picrite, essexite, and a new 

 ijolitic rock containing much analcite, also occur. The age of 

 this monchiquite is definitely fixed by its mode of occurrence. 

 It belongs to the widespread suite of alkaline igneous rocks of 

 Late Palaeozoic age so abundant in the West of Scotland. 

 The .Argyll, Mull and Colonsay examples are believed to be of 

 Tertiary age, but may well be older. They have the usual 

 north-west trend of the Tertiary suite, and cut the east-west 

 dykes of quartz-dolerite which are of Late Carboniferous age. 

 The Monmouthshire occurrence is at least post-Old Red 

 Sandstone, and it is noteworthy that it is regarded either as a 

 d\ke with a north-westerly trend or as a volcanic plug. 

 Another significant point is that the only other intrusion into 

 the Old Red Sandstone of this district, that of Bartestree, near 

 Hereford, has been described by Professor S. H. Reynolds, as 

 teschenite, an analcite-bearing dolerite. 



METEOROLOGY. 



By John A. Curtis. F.R.Met.Soc. 



The weather of the week ended August 19th, as set out in 

 the " Weekly Weather Report " issued by the Meteorological 

 Office, was very fine generally, though thunderstorms were 



reported on the 13th and 19th. Temperature was above the 

 a\'erage in all districts, the departures from the mean rising to 

 7'-S in England, S.W. The highest readings were 92 at 

 Tottenham, Cambridge, Raunds and Bath, on the 13th. In 

 the extreme Xorth it was much cooler, and at Baltasound and 

 Lerwick the maximum for the week was only 60°, In the 



West the heat was not excessive, the r^ • • -n at Scilly being 



76, and at Falmouth 74^\ The 1o\m i ngs were 37° at 



Balmoral and at West Liiiton, and J'/ <xi .\arin and Wick. 

 These were the only stations with minima below 40' ; at manv 

 stations the minimum was not below 50', and at some stations 

 not below 60^. The temperature on the grass fell to 32° at 

 Llangammarch Wells and to 35° at Crathes. 



Rainfall was greatly in defect everywhere, except in London, 

 where it was slightly above the normal. At many stations the 

 week was rainless. 



Bright sunshine was in excess of the average except in 

 Scotland, E., where it was normal. In p'ngland. X.W., it was 

 twice as much as usual. 72 hours (70%). while in England. 

 S.E., the value was still higher, 77 hours (76%). The highest 

 individual amounts reported were 88-9 hours (88%) at Brighton. 

 85-1 hours (84%) at Hastings, and 84-7 hours (84%) at 

 Eastbourne. 



The temperature of the sea water round the costs ranged 

 from 54° at Lerwick to 72° at Margate. 



The week ended August 26th was unsettled all over the 

 country. Rain fell on se\'eral days and tlnniderstorms were 

 experienced in almost all parts. 



Temperature was still high, however, though the excess 

 abo\"e the average was nowhere so great as in the preceding 

 week. The highest readings were 85° at Wisley. and 85 at 

 Cambridge and Raunds. In Scotland the maximum was only 

 73°. while in Ireland, at Killarney, it was 74°. 



The lowest readings were 35^ at Balmoral, and 36° at 

 Markree Castle, Co. Sligo. At Westminster the temperature 

 ranged between 56' and 81°. On the grass, however, frost 

 was observed, the readings falling to 30° .at Markree. and to 

 52' at Balmoral and at Llangammarch. 



The rainfall varied a good deal. It was slightly above tbe 

 average in Scotland, X., the Midland Counties, and England, 

 S.E., and considerably above in England. X.E. In all other 

 districts it was in defect. At several stations falls exceeding 

 an inch in 24 hours were reported ; at Portsmouth the amount 

 on the 21st was 1-40 inches, 1-00 of which fell in half-an- 

 hour. 



Bright sunshine was in defect in all the Eastern Districts, 

 and in excess in the Western parts. The most sunny district 

 was the English Channel with 48 hours (49 %) and the sunniest 

 stations were Guernsey 55 -7 hours (57%) and Pembroke 55-1 

 hours (56 %). 



The niean temperature of the sea water ranged from 54 ■ 8° 

 at Berwick to 68-5° at Margate. 



The week ended September 2nd. was fine as a whole, but 

 in Scotland and the Xorth of England rain fell rather 

 frequentl>'. Thunderstorms occurred at various stations 

 during the earlier part of the week. Temperature was still 

 high, the excess above average in England, E., amounting to 

 more than 5^. The highest readings were 90° at Camden 

 Sc|uare. Cromer and Hillington. with 89° at Greenwich, 

 Cambridge and Xorwich. The lowest readings were 34° 

 at Marlborough, and 37° at Nairn and Balmoral. On the 

 grass the temperature fell to 30° at Cnithes and to 28° at 

 Llangammarch. 



Rainfall was in defect in all Districts except Scotland, N.. 

 and Scotland, W. .At Glencarron the total fall for the week 

 was 3-61 inches, and at Fort Wilham 4-16 inches, which in 

 each case was more than twice the average. 



Bright sunshine was in excess in all the Districts, the 

 district means \-arying from 40 hours. (40%! in Scotland, X„ 

 to 62 hours (65 %) in the English Channel. The sunniest 

 station was Jersey, 69-8 hours (74%). .At Westminster the 

 total duration for the week was 54-9 hours (58%). 



The temperature of the sea water varied from 53° at 

 Scarborough, to 70° at Margate. 



