216 



EECEEATIVE SCIENCE. 



JVIt JVToleworthy's Ch 



orner. 



The Atmospherio Clock.— «-Mr. Noteworthy has 

 been much amused by the performance of an atmos- 

 pheric clock, which he regards as a valuable appli- 

 cation to a purpose of utility of the simplest of all 

 natural laws. This clock possesses no mechanism, 

 but indicates the hour by the regular descent of a 

 column of merou'Tr, and might, therefore, with equal 

 propriety, be called the gravitating clock. In the left- 



X 



XI 



XII 



hand cut the clock is represented in its complete form, 

 with the mercury in the inner tube falling till it reaches 

 the bottom. The clock has then to be reversed, and 

 the mercury will traverse the tube again in the con- 

 trary direction, for all it has to do is to obey the 

 law of gravitation. Mr. Noteworthy's young friends 

 have asked him to explain the reason why the mer- 

 cury falls so slowly and regularly as to serve for 

 a time-divider, and he has made the right-hand dia- 

 gi-am to explain the details. There are two glass 

 tubes, ,one within the other. The inner tube con- 

 tains the mercury, and also atmospheric air. At 

 each end this inner tube communicates by a small 

 orifice with the outer tube, and, consequently, the mer- 

 cury, in its descent, has to force the air out of the 

 inner tube to the outer, and thus its rate of descent is 

 regulated. In the cut the arrows show the course of 

 the inclosed air. The descending arrow in the inner 

 tube is the air forced downwards by the weight of the 

 mercury. This air escapes by the small orifice at the 

 end of the tube, passes into the outer tube, and ascends 

 in it, as shown by the two lowermost of the arrows. 



When it reaches the top of the outer tube, it enters 

 the small end of the inner tube, and thus, as fast as 

 tlie air is forced out below, it enters above, as shown 

 by the descending arrow above the mercury. This 

 clock is in no way influenced, or certainly not to any 

 appreciable extent, by the external air, as the outer 

 tube is hermetically sealed. ^The gravitation of the 

 mercury and the resistance of the air in passing 

 through the orifice determine the rate of motion, and 

 the division of the scale of hours is, of course, in 

 accordance with it. It is not only an instructive toy, 

 but a really useful invention. 



BiEDS IN WiNTEE^A Query. — Many of the finches, 

 and other small birds that traverse the fields in 

 " flights" during autumn and winter, are, as regards 

 the sexes, separated into distinct bodies, one " flight" 

 will consist of males only, and another of females. In 

 the case of the robin, which never becomes gregarious, 

 all the birds now seen near the habitations of man are 

 males. What becomes of the females ? Do they haunt 

 deep woods and solitary places ? And how is it that all 

 the robins met with in gardens and orchards, and 

 in other places near towns and villages, are males, and 

 mostly birds of the same season? 



Efflorescence. — Mr. Noteworthy does not believe 

 all he hears, else he would tell of an old porcelain 

 dinner-plate, which by a natural process has become 

 covered with a forest of trees, shrubs, and flowers, 

 while standing on a shelf in a common cupboard. 

 Attracted by a handbill announcing the " startling 

 fact ," Mr. Noteworthy wended his way to No. 2, Wil- 

 liam Street, Shoreditch, and, on payment of sixpence, 

 had a sight of the " Forest of Crystal Shrubs." It is 

 simply a case of efflorescence, and the crystals, formed 

 by some slow decomposition taking place in the clay, 

 force themselves through the enamel, and, in some 

 instances, rise to a height of half an inch in tufts and 

 bundles. In several places portions of the enamel are 

 lifted up by the crystalline growth, and appear like 

 lozenges laid on the flat surface. It is the most curious 

 example of efflorescence Mr. Noteworthy has yet seen, 

 but evidently of the same nature as that which some- 

 times takes place on the face of a newly-built brick 

 wall, when muriate or nitrate of lime oozes out in the 

 form of a chalky powder. This dinner-plate has 

 turned an honest tradesman into a sbo-\vman, and it 

 would perhaps have been better for him had Dame 

 Nature left his cupboard alone. 



Celts in the Drift.' — Mr. Edwards, an inge- 

 nious glass-maker of Birmingham, suggests, in the 

 columns of the Times, tliat the so-called celts may be 

 natural productions. He says, when glass cools too 

 quickly, fragments fly off" from the bulk of a shape 

 and size closely resembling celts, and if masses of 

 flint were at one time heated by subterranean fires, 

 and then cast forth into the air, the rapid cooling 

 of their outer surfaces would cause them to fracture, 

 and so form natural resemblances to works of art. 

 Mr. Noteworthy believes the celts to be celts, never- 

 theless ; that is not an open question. 



