248 Intelligence and Miscellaneous Articles. 



We may conceive the emission of light, of different wave- 

 lengths as the temperature rises, to proceed from the increase of 

 the small vibrations which produce the less-refrangible rays of the 

 infra-red. In this way we could imagine that, by heating a body, 

 every radiation which it gives out would be shifted toward the blue. 

 If the extension of the spectrum in infra-red were limited, it might 

 happen that the entire light given out would be confined, in case 

 of a solid body, to a larger or smaller band in the spectrum, and 

 that at very high temperatures the whole light would be present 

 only in the most-refrangible part*. 



Now w T e know that the spectrum is most extended in the infra- 

 red, and that even in the sources of highest temperature it has a 

 very large extent, as shown by Langley, Abney, H. Becquerel, and 

 others ; so that the deductions of the above-mentioned authors 

 cannot be quite exact. 



Leipzig, February 25, 1884. 



NEW SOLENOIDAL GALVANOMETER. BY E. BOTTCHER. 



A soft iron cylinder, 1 to 1*5 centim. in thickness and 20 centim. 

 in length, is freely suspended by a thread to a spring balance, so 

 that one half just projects from a solenoidal spiral rigidly fixed to 

 the stand of the spring balance. By means of the current which 

 traverses the spiral the iron core is raised more or less ; and the 

 index of the spring balance shows first the weight of the iron core, 

 and then the strength of current. The instrument is thus an elec- 

 tromagnetic one, with the use of elasticity as a measuring-power. 

 One use of this simple instrument is that it can bear pretty violent 

 shocks, and is therefore suited for somewhat rough usage. As 

 regards the graduation of the instrument, the author observes that 

 within certain limits it may be rationally divided ; and he has given 

 the results of these investigations in the form of a table, and ex- 

 plained it by a diagram. If the iron core is drawn to \ or |- of its 

 whole length within the spiral, one observation is sufficient for the 

 graduation within these limits, to deduce the other current-strengths 

 in respect of the pull they exert ; for, according to the above inves- 

 tigation, the latter is proportional to the square of the current- 

 strength, and moreover increases by about 2 per cent, for each 

 centimetre of the rising or sinking core. — Centralblatt f. Electro- 

 technik, v. p. 620; Beiblatter der PhysiJc, viii. p. 48. 



* In this reasoning there is not taken into account the fact that in these 

 very constrained movements, as in solids or in very dense gases, beside 

 the vibrations of high there must also be those of low refrangibility. 



