HA RD W1CKE' S SCIENCE- G OSSIP. 



179 



water. This promotes the rapid concentration of the 

 water into the larger streams. Mr. Read says that, 

 " all three agencies combined are making the 

 surface drainage almost as perfect as if a series of 

 impervious roofs covered the land, and all the flow 

 from them were conducted by pipes into one common 

 channel." Consequently " springs once copious have 

 disappeared, streams formerly perennial alternately 

 overflow their banks and run dry. The natural 

 regulators of the streams having been destroyed, 

 whenever^ there is excessive rain it is rapidly carried 

 into the streams, which, gradually uniting their 

 waters, often constitute floods in larger channels 

 which no human appliances can control." The 

 remedy proposed by Mr. Read is re-foresting the 

 swamps and the higher lands surrounding them and 

 the lakes, as well as restoring the lakes to their 

 former dimensions, or increasing them wherever 

 practicable, by raising the outlet level. A scheme 

 kindred to this has been proposed for creating 

 artificial lakes or reservoirs at the sources of rivers, 

 as at the sources of the Ohio in the Alleghany 

 Mountains, by damming up the ravines of the 

 smaller streams. 



We have made such reservoirs in many parts of 

 Britain, but of course all our operations are on a 

 much smaller scale than those of our big children 

 over the water. The "compensation ponds" in 

 the Pentland Hills, and the reservoir for supplying 

 Edinburgh, are examples among many others. Our 

 experience at Sheffield, on March II, 1864, shows 

 the possible danger of large-scale operations of this 

 kind. The Bradfield reservoir, having an area of 

 76 acres, and holding 114,000,000 cubic feet of 

 water, burst through its embankment six miles 

 above Sheffield, the flood sweeping all before it 

 from the confluence of the Loxley and the Rivelin 

 to the Don. Nearly three hundred people were 

 killed, and property to the value of more than a 

 million sterling was destroyed. 



If the like should happen to the big things 

 proposed in America, the result would be pro- 

 portionate in magnitude, though not likely to be 

 equally disastrous, on account of the sparsity of 

 population over there. 



The Floods of Last May. — Generally speaking, 

 ours is not a land of floods, one reason being that 

 the deep soil so largely prevailing acts as a flood 

 moderator. In countries like Spain, where there 

 are great areas of bare or nearly bare rock-slopes, 

 many rivers are roaring, overflowing torrents in wet 

 weather, and quite dry at other times. It is possible 

 that we may be over-draining, as the Americans have 

 been, and that our recent liability to floods has 

 been thereby induced. At the last meeting of the 

 Meteorological Society, June 16, Mr. W. Marriott 

 read a paper on the floods of May connected with 

 the heavy rains between the nth and 13th. At 



Worcester the flood was higher than any that have 

 occurred there since 1770. The West and Midland 

 counties suffered generally in like manner. At 

 Shrewsbury the Severn rose 16 feet above average 

 summer level, and at Worcester 17 feet 1 inch. At 

 Ross, on the Wye, the flood was ' 14 feet. At 

 Nottingham the Trent rose 12J feet ; at Rotherham 

 the flood was 8 feet 5 inches ; and in north-east 

 Yorkshire the Derwent rose nearly n feet above 

 summer level. Great damage to property was caused 

 by these floods, and considerable loss of life ; bridges 

 were washed away, railway traffic suspended, and or- 

 dinary business seriously interrupted. In some places 

 the waterworks were flooded, with the paradoxical 

 result of cutting off the water-supply to the towns. 



Mountain Observatories. — In 1858 Piazzi 

 Smyth, Her Majesty's Astronomer for Scotland, 

 published a very interesting book entitled, " Tene- 

 riffe : an Astronomer's Experiment." This experi- 

 ment, made during the summer and autumn of 1856, 

 consisted of erecting an observatoiy at a great 

 elevation, and making astronomical and meteoro- 

 logical observations there. The height of the 

 observatories in this case amounted to 8900 feet 

 at one station, and 10,700 feet at the other. 



Piazzi Smyth was thus the pioneer in the work of 

 high-station astronomy and meteorology, which have 

 now become greatly developed ; but among the 

 admiring accounts of such work that I have seen 

 I do not find a fair acknowledgement of his priority, 

 and his practical demonstrations of the advantages 

 of such observatories. The latest of these is one in 

 course of erection on the Sonnenblick, 10,170 feet 

 high (Tyrolese Alps). This is the highest now in 

 Europe, where there are about a dozen others at 

 elevations of 4000 feet and upwards. The highest 

 in the world is that of Pike's Peak, Colorado, 

 14,134 feet. The majority of these are only 

 meteorological observatories. Piazzi Smyth com- 

 bined astronomy and meteorology, and by selecting 

 Teneriffe, on an island so far out at sea and rising 

 so sharply from it, obtained at a given elevation far 

 greater freedom from dust-haze than is possible at 

 any of the inland observatories. 



Spots on Sycamore-leaves. — W. B. Drummond 

 will find an answer to his query in Science- 

 Gossip for October 1884, where it is said: "The 

 black spots and patches on the leaf of sycamore have 

 been caused by drops of rain or dew acting as sun- 

 burners by condensing the solar rays." I think I 

 have myself noticed those spots on the leaves of some 

 other tree, though I cannot at present remember 

 which. It would, however, be interesting to know, 

 as Mr. Drummond suggests, why they are confined 

 altogether or for the most part to the sycamore or 

 plane-tree.— J. Muir, Glasgow. 



