Oct. 17, 1872] 



NATURE 



493 



Academy of Sciences will be found of interest as bearing on this 

 question. Writing from Rome on the 27th of August, he says 

 (Cotnt'cs Raidiis, p. 613I : — "(In the 15th of this month we had 

 an Aurora Borealis by day, at ten o'clock in the moniing up to 

 midday. The magnetometers were greatly disturbed, and in 

 the heavens at half-past ten appeared an arch of light cirrus 

 clouds, stretching from N.N.W. to N.E., and crowned along the 

 whole of its contour by numerous and fantastic rays {jds fila- 

 nuntciix). The forms of these rays so perfectly resembled those 

 of the solar protuberances that some of the drawings of them 

 might easily be mistaken for drawings of solar protuberances even 

 by people well accustomed to these observations." 



Mcrton College, Oxford J. P. Ear\v.\ker 



Meteor 



Last night, Oct. 9-10, about midnight, G.M.T. a meteor was 

 seen by my wife in the S., considered by her to rival the bright- 

 ness of Venus, and describing a path which was so carefully 

 sketched by her immediately afterwards as to form a possible 

 basis of comparison ; and which therefore may be thought 

 worthy of insertion in Nature. It seems to have become 

 visible near f Ceti, probably rather ///that star (which, however, 

 was not noticed by her through a dewed window-pane), and to 

 have passed with a slow motion and a yellowish light, in a path 

 somewhat convex towards the zenith, in tlie direction of /3 Ceti, 

 before reaching which it vanished. For about three-fifths of its 

 course it preserved the same aspect, as of a ball of light with 

 sparklings round it, and some appearance of a train ; but in its 

 further progress it seemed to waste away to extinction. 



T. W. Webb 



Ilardwick Vicarage, Herefordshire ; according to Ordnance 

 Map, long. W. 3h. 4m. 23s., lat. N. 52° 5' 20". 



Fossil Oyster 



I HAVE recently noticed a fossil oyster, in what Sir C. Lyell 

 calls the Lower Miocene, or Ilampstead beds. Can you, or any 

 of your readers inform me if it has been noticed before. lean 

 find no mention of it, in any work within my reach. I have been 

 a subscriber, from your first number ; and have observed the 

 kind notice you have extended to other inquirer.', and have thus 

 been emboldened to trouble you. Inquirer 



N.B. — I have no pretensions to science, or any scientific 

 acquaintance, being merely a solitary observer. 



A^'' ELECTRICAL BAROGRAPH 

 I HAVE recently designed a barograph, a brief .iccount 

 i. of which may be interesting to your readers. The ad- 

 vantages claimed are : — 



That the record may be seen as it is going on. 



That it is quite as, if not more sensitive than, the photo- 

 graphic barograph, and the scale is larger. 



That no time is lost preparing the paper, printed forms 

 answering the purpose. 



That the first cost and cost of working are both much 

 less than in the photo-barograph. 



A photograph has been taken which shows the instru- 

 ment in working order, with part of a day's record sliown 

 on the cylinder.* 



The cylinder is ten inches long, and eight inches in 

 diameter, allowing for one inch per hour of paper. 



The clock, or governor, is connected by a bar to 

 a movable inclined plane, this is again connected by 

 a bar to the long wire parallelogram which carries 

 the pen, and the clock, by means of an eccentric, 

 causes the inclined plane, and with it of course the pen 

 frame, to move backwards and forwards once every 

 minute. The wire frame is guided by four brass friction 

 wheels, attached to a brass frame having motion up 

 and down only ; under it are the coils of an electro- 

 magnet, the armature of which is attached to the brass 

 frame. So long as no electricity passes through the coils 

 the brass frame is thrown up by a small spring high 

 enough to lift the pen off the paper. 



A photograph and section were obligingly forwarded by the author /vilh 

 hia description. 



The barometer tube is an ordinary glass one o'58 

 in diameter, and is fixed firmly to the case. Its cis- 

 tern is a small glass one, one inch in diameter, and 

 cemented to a brass arm hinged to the left side cf the 

 case, and which allows it perfectly free motion up and 

 down, but not sideways. From tliis cistern projects a 

 very light arm, also hinged, and bent at the end so as to 

 extend over the inclined plane. One wire of the battery 

 is attached to the cistern arm, and the other, after passing 

 round the magnet, to the inclined plane. As soon, then, 

 as these two parts touch, the electro-magnet brings down 

 the brass frame, and with it the pen, on to the papers 

 which at once begins to mark, and continues to do so 

 until the motion of the clock draws the incUned plane 

 from the cistern arm, and so breaks the contact ; the pen 

 remains off the paper until, by the motion of the clock, 

 the inclined plane is brought to touch the projecting cis- 

 tern arm, when the pen at once begins to write. As the 

 barometer, when the pressure increases, must draw the 

 mercury for its increased height from the floating cistern, 

 the cistern becomes lighter, and rises with it, and the 

 smallest motion may be made sensible by altering the 

 inclination of the moving inclined plane. The accuracy 

 of the motion of this plane is secured by making it work 

 on two fine steel points — the same motion, in fact, as that 

 given to the cutter of a dividing engine. The cistern floats 

 in a reservoir of mercury. 



The pen is a syphon pen, supplied with thin ordinary 

 writing ink. H. C. RtJSSELL 



Sydney Observatory, Aug. 10 



BE A UFORT'S WIND SCALE AND THE BOARD 

 OF TRADE* 



'T^HE Board of Trade have recently issued instructions 

 -*- to Receivers of Wreck and Ofiiccrs of Coastguard, 

 with reference to Beaufort's Wind Scale, so that one 

 uniform construction should, as far as possible, be placed 

 upon the wind scale by them. In the Circular the follow- 

 ing passage occurs : — 



" The Board of Trade are led to think that different 

 constructions are placed by different persons upon the 

 scale known as Beaufort's scale. In illustration, it may 

 be remarked that the higher forces, 1 1 and 12, are, as the 

 Board learn from the Meteorological Committee, scarcely, 

 if ever, reached in the British Isles. Force 12, which is 

 intended to represent a West India hurricane, the velocity 

 of which is 80 miles per hour and upwards, has been 

 reached only twice in four years on the coasts of the 

 United Kingdom ; notwithstanding high winds prevailing 

 at the time of a wreck are frequently described by the 

 ships' officers as storms or hurricanes." 



It is here taken for granted that the positions of the 

 anemometers of the Meteorological Committee are such 

 as to record observations of wind fairly comparable with 

 those felt at sea ; and also that the anemometers are con- 

 structed to record those velocities of the wind which are 

 applicable to the case in hand. 



It is not stated how the two instances of velocity of 80 

 per hour and upwards were ascertained. Since, however, 

 the space traversed or recorded by the anemometers at 

 the observatories of the Meteorological Committee can 

 scarcely be measured for a shorter period of time than 15 

 minutes, it may be assumed that on two occasions, and 

 only on two occasions during four years, have the anemo- 

 meters been noted to record a velocity of 20 miles or 

 upwards in 15 minutes — that is, a velocity at the rate of 80 

 miles an hour or upwards. If the tracings of the Hemi- 

 spherical Cup Anemometer could be read oft" for so short 

 a period as five minutes, many instances of So miles an 

 hour, and even several velocities of 100 iniles an hour and 

 upwards, could be taken from the records of these four 

 * See Cir.jlar, No. 558. 



