Nov. lo, 1887] 



NA TURE 



31 



Royal Society, that Her Majesty's Consul-General at Christiania 

 has reported that a considerable number of pits of " infusorial 

 earth " containing 85 to 95 per cent, of silica are said to have 

 been discovered in the neigbourhood of Stavanger. 



Capital is being sought for the purpose of working the 

 deposits, which are estimated to be capable of yielding 4CX),ooo 

 cubic metres of that rare product. It is affirmed that whilst the 

 similar deposits at Liineburg, in Hanover, are mixed with sand 

 and gravel, those now discovered are so pure in quality as to be 

 available for most purposes merely after desiccation. 



As this discovery may possibly have a scientific interest as 

 well as a commercial value, I am directed to convey the above 

 information to the Royal Society. 



I amj Sir, your most obedient humble servant, 



T. V. Lister. 



The Secretary, Royal Society, Burlington House. 



The Electrical Condition of the Peak of Teneriffe. 



The limited number of observations on atmospheric electricity 

 which have been already made all point, with one exception, to 

 a normal positive difference of potential between a point some 

 few feet above the earth and the ground itself. The only notable 

 exception to this law was found in some observations which were 

 made on the Peak of Teneriffe about thirty years ago. Then it 

 appeared that the condition of the Peak was constantly resinous 

 or negative. These observations were, however, taken with a 

 gold-leaf electrometer, and some doubt has been expressed as to 

 whether the sign of the electricity was correctly obtained. 



I therefore thought, when taking a short trip to Teneriffe, that 

 it would be useful to examine this question by means of the 

 improved electrical instruments now available. 



Through the courtesy of the Meteorological Office I obtained 

 the loan of a Thomson's portable electrometer, and, through the 

 kindness of Mr. Whipple, received at Kew all necessary instruc- 

 tion in the use of the instrument, and special caution as to the 

 possible difficulty of getting a good "earth" on sun-burnt lava. 

 Any success the observations may have had is entirely due to his 

 care and forethought. 



I was only able to stay about a fortnight on the island, but the 

 results obtained were so uniform that there can be no doubt as 

 to their accuracy. 



The height of the electrometer fuse was always about 5 feet 

 6 inches above the ground. At the Port of Orotava, at the 

 base of the Peak, and about 50 feet above sea-level, the mean of 

 eight sets of observations — each set usually consisting of six 

 determinations^ — gave a potential of 138 volts. The highest 

 was 193, and the lowest 98 volts. These, and all I obtained in 

 Teneriffij, were uniformly positive. 



One day I took a skirmishing expedition to the rock of Gayga, 

 a portion of the rim of the old crater, 7100 feet above the sea. 

 On the way up, while on the pretty uniform slope of the moun- 

 tain, at 3800 feet, the potential was only -f 99 volts, while on 

 the rock itself, tension rose to 257 volts. The rock is a long 

 sharp, narrow edge, perhaps half a mile long, with a precipitous 

 cliff of 500 feet on one side. The rock was composed of dry 

 lava, and I thought a little damp, but still the earth observations 

 were not quite so accordant as usual. 



A few days later, therefore, when starting for the top of the 

 Peak, I took, as suggested by Mr. Whipple, an ordinary 66-foot 

 iron surveyor's chain to be laid along the ground and connected 

 with the instrument. The readings at different heights, on the 

 way up, were as follows : — 



At 5600 feet, on the slope of the mountain, in volts. 



On the Cafiadas, or rough flattish ground that forms the bottom 

 of the old crater, at 5800 feet, 139 volts. The ground here was 

 pumice and pumice dust, so I tried running out the chain to see 

 if the earth-readings would be altered. There was not however 

 the slightest change, and to show the character of the observa- 

 tions five out of the six earth-readings gave the same number. 



At the Estancia de los Ingleses, 10,500 feet, situated on the 

 slope of the main peak, the potential fell to 118 volts. The sun 

 was setting, and dew falling so fast that the top of the electro- 

 meter box was covered with wet. There could be no doubt then 

 of obtaining a good earth. 



On the top of the Peak, 12,200 feet, the potential actually rose 

 to no less than 549 volts. This was at 8 o'clock in the morning 

 of October 24. The wind was blowing at the rate of about 

 lo miles an hour from the north-east, while the dry and wet 



bulb thermometers marked 31° and 26° respectively. There was a 

 little white frost on the ground, and the earth- readings, without 

 the chain, were remarkably uniform, only differing by the ii-iooth 

 of a turn of the screw. 



The results of all the observations points unmistakably to the 

 conclusion that during this month of October the electrical 

 condition of the Peak of Teneriffe were the same as in every other 

 part of the world. The potential ivas moderately positive at the 

 same distance from the ground tven at considerable altitudes, but 

 the tension rose enortnously round a sharp point, and a projecting 

 edge of rock. 



It is well known that there are very few thunderstorms in 

 Teneriffe, though one passed near us at Orotava without affect- 

 ing the indications of the electrometer. Would it not be 

 interesting to measure the potential on the summit of a mountain 

 like Kina Balu in Borneo, which is about the same height as 

 the Peak of Teneriffe, but situated in the heart of the equatorial 

 zone of the constant electrical discharge ? 



We had one day of very heavy rain, when possibly some 

 negative indications might have been obtained ; but I did not 

 think it expedient to let the instrument get drenched. 



But, besides obtaining these decisive electrical results, I was 

 alsi very fortunate in some other observations during the short 

 stay in Teneriffe. 



We saw from the Estancia the shadow of the Peak at sunset 

 gradually creep along the land and surrounding sea, and then 

 stand up in the air like another peak rising above the horizon. 

 This is what is so often seen from Adam's Peak in Ceylon, and 

 from Pike's Peak in Colorado. 



Then our observations confirmed not only the important 

 discovery made by P. Smyth, that cloud is not formed at the 

 junction of a south-west current flowing over a north-east trade, 

 but the even more important fact that there is no such thing as 

 the supposed simple return current from the equator. At 

 Teneriffe, as in every other part of the world I have ever visited, 

 the general circulation of the air is on a complicated screw 

 system, the practical effect of which is that as you ascend, the 

 wind always comes more and more from your left hand as you 

 stand with your back to the wind. You do not come abruptly 

 to a south-west wind over a north-east trade, but pass succes- 

 sively as you rise from the surface from north-east through south 

 to south-west, and then probably to west, or even north-west. 



I also made some very important observations on the local 

 formation of halo-forming sky, and got an excellent photograph 

 of the genesis of a cirrus cloud from a moist current rising over 

 the Peak, but space will not allow me to explain the results in 

 this place. Ralph Abercromby. 



21 Chapel Street, London, November 7. 



"Toeing" and "Heeling"' at Golf. 



I FEAR that " P. G. T.'s" reply to my letter on the above sub- 

 ject has left us very much in the same position as before. This 

 is regrettable, as I hoped that further light would have been 

 shed on this interesting mechanical problem. Before complying 

 with the invitation to "think over the result of the impulsive 

 rotation of the club-head," I considered it would be well to get 

 some trustworthy observations on which to reason. With this 

 object our professional, Mr. David Lowe, made twenty -seven 

 tee shots with the driver, while I noted the effect. My instruc- 

 tions to him were, whether striking off the toe or the heel, to 

 drive as truly as he could in the direction of an object selected 

 for that purpose. The effects were as follows : — When the ball 

 went off the heel of the club, the ball in its flight curved to the 

 right, even though its direction commenced obliquely to the 

 left ; to this there was no exception. The opposite curve, or to 

 the left, with only one exception, was produced by hitting off 

 the toe. Care was taken to ascertain in each case the point of 

 impact of the ball on the club-face. 



1 now instructed him to try and curve the ball to the left, 

 striking with the heel of the club, or to "toe it off the heel, in 

 " P. G. T.'s " words. This feat he was unable to perform, and 

 he gave it as his opinion that it could not be done. 



Now for my explanation of "toeing " and " heeling m reply 

 to the invitation of " P. G. T." 



Everyone who has played golf is aware that the ball when 

 cleanly struck leaves a round mark upon the face of a new club 

 of about five-eighths of an inch in diameter. This is the measure 

 of the elastic distortion that takes place in the ball by^the 



