September 23, 1892.] 



SCIENCE. 



177 



sand, resting in one place on end, and much mixed on the sur- 

 face, sides, and end with gravel and fossils belonging to later 

 formations. Bones of whales and fragments of shells of the 

 Miocene Formation have settled into its broken surface ; but in 

 the unmixed interior of the mass, it has yielded to me soft casts 

 of Gryphea and CucuUea, hard fragments of the bones of reptiles, 

 with coprolites, and teeth of the shark Otodus. The component 

 materials of this marl agree with those of the Lower Marl of New 

 Jersey, and, like the latter, rest directly upon the upper member 

 of the Karitan Formation. 



The Miocene Formation, so far as. my own observation ex- 

 tended, is broken up, and so mixed with the drift at the base of 

 the glacial deposits near the surface that the only evidence of its 

 former presence here, below the belt of conglomerate, resides in 

 the presence of vertebree of Cetacea, fossil shells, and some teeth 

 of sharks. 



On the surface is the fine pale sand, forming a loose bed, under- 

 laid by about two feet of pebbly conglomerate which rests in a 

 bed of broken rocks, gravel, and boulders. The sand is spread 

 thickly over most parts of the island, and along the western ridge 

 it is set with granitic boulders measuring occasionally twelve 

 feet in length and width by six to eight feet in thickness. 



The whole Gay Head promontory is a scene of disturbed equili- 

 brium, where the beds of rock-derived material have been soft- 

 ened by atmospheric agencies, pressed down by a load of stone 

 and gravel, undermined by oceanic strokes of oceanic surf, and 

 let down into gullies by trenching storms of rain. 



the cloud until light rain began to fall. Is my experience as 

 given a common one? Was it a dangerous one? 



O. C. Chablton. 



Denton, Texas. 



The Gemination of the Lines in Mars. 



As far as one can judge from newspaper reports, the recent ob- 

 servations on Mars render certain the existence of the curious 

 Schiaparelli lines, but as yet nothing has been seen of the doub- 

 ling, or gemination, which has been claimed. If this negative 

 result shall be sustained by the accounts yet to come from obser- 

 vatories in lower latitudes, there still remains the interesting 

 question. How did such a mistake come to be made? 



A bit of personal experience will, I trust, be pardoned, since it 

 points to what seems to me the explanation of the error, if one 

 exists; at least, it shows the existence of a vera cauxa able from 

 single lines to produce double ones. The lens in my left eye pos- 

 sesses the power of double refraction. If I clo.-ie the right eye and 



look at a line drawn obliquely, thus 



the paper being held 



squarely in front of me, I see nothing peculiar; there is to me, as 

 to anyone else, only one ordinary black line. But if the line 



slopes thus 



I see two lines 



the lower one being 



LETTEES TO THE EDITOR. 



#*# CoiTespondents are requested to be as brief as possible. Tlie lorizer's name 

 is in all cases required as proof of good faith. 



On request in advance, one hitndred copies of the number containing his 

 communication will be furnished free to any correspondent. 



The editor will be glad to publish any queries consonant loith the character 

 of the journal. 



A Mountain-Top Experience. 



Fremont Pass, Colorado, is 11,540 feet above the sea. To the 

 east rises a peak by a rather steep slope, perhaps , 2,000 feet 

 higher. Its eastern slope is precipitous. 



On Aug. 18, alone, I reached the summit of this pepk. It was 

 noon. Several miles away to the north a heavy thunder-storm 

 was raging, while far to the west was another. Within a mile 

 or two a massive cloud had formed between the lower mountains 

 which shut in a gorge. I stepped to the very highest point of the 

 peak. My contemplation of the extraordinary view afforded me 

 was disturbed by a sharp buzzing as of bees seemingly beneath 

 my hand which rested on the bulky pine sliver serving as my 

 staff. But on lifting my hand I found no bees large or small. 



As the buzzing continued, I vainly scrutinized the stick for 

 signs of life. I then indifferently concluded that it was possibly 

 caused by some boring insect in the wood. That settled (?), I 

 lifted a large roundish rock to toss into the chasm below, when 

 it, too, buzzed or crackled in my hand at a score of points. Close 

 inspection revealed no bees or bugs on that rock. Can it be. I 

 asked, that this rock is crackling from the change of temperature 

 occasioned by a change of position ? At that moment, the 

 "bees" were swarming in my hat. Snatching it off, I was 

 searching it for the buzzing things when they seemed to throng 

 my hair. Immediately on raising my hand to my head the puz- 

 zling mystery was solved, as the strong flow of electricity fairly 

 tingled and buzzed through my fingers, and, looking up, I saw a 

 cloud forming overhead. I was acting as a lightning-rod to that 

 mountain-peak. Ignorant of my possible safety or danger in the 

 involuntary experiment, I lacked the valor or scientific devotion 

 to prolong it. Securing my box of flowers and that buzzing staff, 

 I discreetly retired some distance down the slope from that sum- 

 mit surcharged with possible electrocution if I remained. Ere I 

 reached the pass, two hours later, the storm from the north had 

 reached the peak, and soon that rocky summit was whitened with 

 snow, while hail and rain fell in the pass. 



During my descent, while the thunder-cloud rapidly approached 

 the peak, a strong wind blew through the pass directly toward 



decidedly less deeply black than the other. As I now hold the 

 paper, the bottom towards me, No. 1 appears as a single line, 

 No. 2 as a double one, like No. 3. If now I turn the side of the 

 page towards me, revolving it through an arc of 90", No. 1 shows 

 double and No. 3 single. 



If I draw a set of single lines as below 



and look at them with both eyes, or with my right eye alone, I 

 see only so many single lines; but if I close my right eye, then 

 with my left I see ten lines, each original line being geminated by 

 a fainter one exactly parallel, and pretty close to it, as in No. 5. 



If now I turn No. 4 to the right or left, the double images will 

 approach each other, and at the same time slide by each other a 

 little until I have turned the paper 90°, when the images will 

 coalesce, each line appearing sharply defined, single, and very 

 black, except at each end, where for about -jV of an inch the color 

 will be fainter and the line less sharply defined. I can vary my 

 experiments in many ways, each time getting the well-known 

 phenomena of double refraction. 



The application to the lines in Mars is very simple. If a person 

 possessing an eye with this power should see the planet's image in 

 the telescope, and be able to perceive the Schiaparelli lines, he 

 would see each accompanied by a twin line of the same length, 

 but not quite so sharp and distinct. If the lines ran, as in No. 1, 

 from north-west to south-east, he would not see the secondary 

 ones, but if his other eye chanced also to have a double refracting 

 lens with axis at right angles to the first, he would then see the 

 secondary lines in the same way. 



I know, from my own experience, that one may possess this 

 power without being conscious of it. I discovered it only when 

 experimenting on single vision. In ordinary use (i. e., with both 

 eyes) I cannot perceive any indication of it, the greater illuminat- 

 ing power of the ordinary ray, plus that of my other eye, com- 



