Oct. 1st, 1887.] 



SCIENTIFIC NEWS. 



183 



NOVEL LANTERN SLIDE. 



'IPHE engraving shows an inexpensive and very simple 

 and effective device for exhibiting the action of the 

 circulating fountain upon a screen. It consists of a glass 

 tube of small diameter bent into the form of a volute, with 

 the inner end of the tube extended laterally, and then bent 

 vertically, a funnel being provided at the upper extremity. 

 The table at the outer end of the spiral is bent outward 

 radially, then downward at right angles. The tube thus 

 bent is mounted on a board having a circular aperture a 

 little larger than the spiral, so that the entire spiral may be 

 strongly illuminated, while the ends of the tube leading to 

 and from the spiral are concealed by the board. Above the 

 funnel there is a reservoir with a small opening at the bot- 

 tom, and through this a pointed wooden rod extends down- 



wards into the tube below, and forms a valve for regulating 

 the flow of liquid. The liquid employed is water, to which 

 has been added some colouring matter, such as aniline 

 blue, red, or green. A few drops of aniline red ink 

 answers for this purpose. The flow of the liquid is started 

 by loosening the valve, so that the water drops regularly 

 into the funnel of the tube below. The drops should fall 

 intermittentlj', so as to include air spaces between them. 

 The liquid, as it issues from the downwardly turned end of 

 the spiral, is received in a cup, by which it may be returned 

 to the reservoir, and so used again. When it is desired to 

 accelerate the motion of the liquid in the tube, a short 

 rubber tube is connected with the end of the glass tube 

 which is bent downwards. The glass tube should be about 

 one-sixteenth of an inch internal diameter, and the spiral 

 about three and a half inches in diameter. When the 

 fountain is in operation, the spiral seems to revolve, but 

 each convolution appears to turn at a different rate of 

 speed, owing to its increasing diameter. When projected 

 with a good lantern and a strong light, it becomes a very 

 interesting object. — Sciiiitific Aincrkau. 



CLINICAL THERMOMETER. 



AT the Inventions Exhibition, Mr. Immisch showed a very 

 , compact and ingenious clinical thermometer which at- 

 tracted much attention. Since then he his further improved 

 it, and has made it suitable for veterinary as well as other 

 purposes. Fig. r is a full-sized view of the thermometer. 



which is only one inch in diameter, and has the appearance 

 of a locket. Its action depends on the movement of a spiral 

 metal tube which is filled with a liquid which expands and 

 contracts with variations of temperature. The movement 

 of the tube is transmitted to the pointer by a simple me- 



Fig. I. Clinical Thermometer (full size). 



chanical device, and as the spiral tube can move without 

 appreciable resistance it accurately records the changes of 

 temperature it is subjected to. There is a further advan- 

 tage due to the fact that the tube is always full of liquid, so 

 that the pointer is not affected by changes of atmospheric 



Fig. : 



Thermometer with Flexible Handle for Veterinary 

 Purposes. 



pressure. The thermometer is now fitted with a stop ar- 

 rangement, so that the pointer can be fixed when required, 

 and there cannot be uncertainty as to the reading of the 

 temperature taken. It is stated that the authorities at Kew 

 have satisfied themselves as to the permanency and reli- 

 ability of these instruments, and that they omit as unneces- 

 sary the usual caution they give with glass thermometers as 

 to their liability to change with time. Fig. ?. shows an 

 instrument provided with a fiexiblc handle wliich can be 

 attached, when required, for veterinary purposes. 



THE SIZE OF THE SUN AND MOON. 



IT is strange that few people can indicate the height of 

 so well-known an object as a " chimney pot " hat, by a 

 mark on the wall, without making an error of from one- 

 third to one-half in excess. This is nothing compared with 

 the diversity of opinion as to the apparent size of the sun 

 or moon. Few persons who have not some acquaintance 

 with scientific measurements understand that to say the 

 moon looks " as big as a plate," expresses nothing, though 

 it at once becomes an intelligible estimate when the dis- 

 tance at which the plate is supposed to be, is given also. 



Enquiries from a dozen people will elicit guesses varying 

 from " the size of a threepenny bit " to " a cartwheel," but 

 on being asked further, at what distance from the eye these 

 objects are supposed to be, the replies will be given with 

 some hesitation. 



It might be imagined that the distance, which is almost 

 invariably omitted at first, would be the distance at which 

 one would most often see the object, such as a threepenny- 



