June 1st, 1SS7.] 



SCIENTIFIC NEAVS. 



n 



The Number of Visible Stars. — According to the com- 

 putations of M. Hermite, a French astronomer, the total 

 number of stars visible to the naked eye of an observer of 

 average visual power, does not exceed 6,000. The northern 

 hemisphere contains 2,478, and the southern hemisphere 

 contains 3,307 stars. In order to see this number of stars, 

 the night must be moonless, the sky cloudless, and the at- 

 mosphere pure. The power of the naked eye is here 

 stayed. By the aid of an opera glass 20,000 can be seen, 

 and with a small telescope 150,000, while the most power- 

 ful telescopes will reveal more than 100,000,000 stars. 



Artificial Whetstones. — We take the following descrip- 

 tion of a method of making artificial whetstones, from the 

 Guide ScieiUifiqite. Gelatine of good quality is dissolved in its 

 own weight of water, the operation being conducted in a dark- 

 room. To the solution i| per cent, of bichromate of potash 

 is added, which has previously been dissolved in a little 

 water. A quantity of very fine emery, equal to nine times 

 the weight of the gelatine, is intimately mixed with the gela- 

 tine solution. Powdered flint may be substituted for emery. 

 The mass is moulded into any desired shape, and is then 

 consolidated by heavy pressure. It is dried by exposure to 

 strong sunlight for several hours. 



Paper B.\rrels. — During the last twenty years various 

 attempts have been made to produce a paper barrel that 

 would answer all the purposes for which the wooden barrel 

 is used. Recently a barrel has been produced from paper 

 pulp, its general appearance being that of the common 

 wooden barrel thickly varnished, vv'hile only five pieces are 

 used in making it. It is bound with ordinary wooden 

 hoops, and the head is of one piece, so constructed that it 

 fits into the barrel air-tight, and is held firmly in place by a 

 hoop without the use of nails. The body is seamless, and 

 the interior and exterior are glazed with a substance which 

 renders the barrel impervious to moisture, so that liquids 

 can be transported in it without loss. 



Telepho.ve Diaphragms. — M. Mercadier, in a memoir pre- 

 sented to the Paris Academj' of Sciences by M. Cornu, con- 

 tends that the transmission of articulate speech is chiefly, if 

 not solely, the result of molecular motion in the plate of the 

 telephone receiver. Vibrations of the plate as a whole are 

 only capable of yielding a single tone and its harmonics. 

 This tone remains unaltered when the plate is supported at 

 various points which are nodal points for this particular note, 

 but under these circumstances the transmission of other tones 

 is much enfeebled. Such an instrument M. Mercadier calls 

 a mono-telephone. On the other hand, a diaphragm 

 supported in such a manner as to be incapable of performing 

 transversal vibration is still able to transmit speech with per- 

 fect clearness, although with considerable diminution of in- 

 tensity. 



Electricity for Farming Purposes. — An interesting 

 account has lately been given before the Farmers' Club of 

 the employment of electricity on the Hatfield estate, 

 belonging to the Marquis of Salisbury. It appears that at 

 Hatfield electricity is now used for woiking elevators to 

 build up the hay and corn stacks, for cutting the rough 

 grasses into chaff" for ensilage, for grinding barley, maize, 

 etc., for cattle feeding. It is also used for pumping sewage 

 on to the higher lands, and arrangements have been made 

 to thresh by it. The power required is obtained from a 

 river which runs through the estate, there being a water- 

 wheel in a central station, so that the cost of the power is 

 merely nominal. 



The Inner Structure of Cast Steel. — Some interesting 

 experiments have been recently made on this subject by 

 MM. Ormond and Werth, of the Creusot Works. A very 



thin rolled plate was placed on a pane of glass and carefully 

 treated with nitric acid until the iron was all dissolved, in 

 such a way as to leave the carbon in its normal condition. 

 Upon examining the skeleton with a microscope, it was 

 found that the carbon was very unevenly distributed 

 throughout the mass, and that the inner structure of the 

 steel consisted of very small particles of soft iron en- 

 closed in cells formed by the carbon. These cells were 

 distributed in the iron, either combined or as a collection of 

 cells having considerable open spaces between them, so 

 that such a plate or sheet of steel may be rolled until it be- 

 comes transparent. These spaces are irregular in shape, 

 and even in the raw material may be almost noticeable, but 

 they are reduced in proportion to the treatment to which 

 the steel is subjected either by rolling or hammering, as 

 naturally its homogeneity is then increased. 



The Influence of Basic Cinder on Plants. — Some 

 experiments made on the influence of the ferrous oxide in 

 basic cinder on the growth of plants, was recently described 

 by Mr. J. M. H. Munro. He says : — Seeds of various kinds 

 — barley, white turnips, clover, white mustard, garden 

 cress — were sown in garden soil mixed with basic cinder, 

 for the purpose of ascertaining whether the large amount 

 of ferrous oxide in the basic cinder in any way hindered 

 the germination or growth of the plants. In order to 

 test this thoroughly, very large quantities of basic cinder 

 were used, viz., ten per cent, of the mixed soil, twenty-five 

 per cent., fifty per cent, and pure basic cinder without any 

 soil. Most of the seeds germinated even in the pure basic 

 cinder, and some of the plants lived until starved for want 

 of nitrogenous food. All the other mixtures produced plants 

 which flowered and seeded in due course ; the barley 

 plants, in the equal mixture of basic cinder and soil, being 

 actually better than those planted in garden soil only, and 

 producing full ears of grain of unimpaired germinating 

 power. 



The Red Spot ox Jupiter. — From our German contem- 

 porary, Hiunl'oldt, we extract the following :— Since the year 

 187S an oval red spot on Jupiter has been attracting the 

 attention of astronomers. It lies about thirty deg. south of 

 the Equator, and is about 6,000 geographical miles long, and 

 1,300 miles in width. During the first three years it could 

 be seen very plainly, but in 18S2 it became faint, without, 

 however, changing its shape; in 1SS5 it was partly covered 

 by a whitish cloud, which threatened to veil it entirely, but 

 which has now withdrawn, and left the spot as visible as in 

 18S2 and 1S83. It is remarkable that its rotation-time from 

 1879 until now, has steadily increased from 9 hours 55 

 minutes 35 seconds, to 9 hours 55 minutes 40 seconds, also 

 that whilst with Jupiter generally, as with the Sun, the 

 angular velocity increases towards the Equator, the angular 

 velocity of the spot is less than that of the prominent points 

 in higher and lower latitudes. 



The Protection of Iron. — Hitherto the preservation of 

 iron has been effected in very different ways. One method 

 has consisted in converting its surface into an oxide, another 

 in applying paint or enamel, another in coating it with zinc 

 — a metal more readily attacked than itself. All these 

 methods bear the aspect of being expedients merely, and 

 do not present a definite solution of the problem. Of all 

 the ordinary metals, lead, which resists some of the stronger 

 acids, such as sulphuric or hydrofluoric, may be regarded 

 as the most durable. From the Scientific American we 

 learn that a new process for coating iron with an adherent 

 layer of this metal has recently been discovered and per- 

 fected by Mr. F. J. Clamer, of Philadelphia. By it the iron 

 is covered with a uniform coating of silvery lead, the rough- 

 nesses and indentations of the iron receiving the lead, as 



