i873«] Heat. 279 



the same time made the discovery of the aberrations caused by covering the 

 object with a film of glass, and applied the means for their correction. Mr. 

 Wenham then described the increase of aperture obtained by the use of the 

 triple front lens. This was followed by Mr. Lister's introduction of a triple back 

 lens in the year 1850, by which the aperture of the £th was increased to 130° 

 or more, and this form was employed for high powers until quite recently. 

 The next advance was Mr. Wenham's discovery of the feeble correcting power 

 for colour of the flint concave in the triple front, and his successful substitution 

 for it of a thick single lens, the form now usually employed in the best high- 

 power objectives. His attempt was to substitute a single lens in place of the 

 middle doublet. This, however, for reasons shown in his diagram, failed to 

 produce the desired result, and led to the employment of a triplet between two 

 single lenses. By this means perfect corrections were obtained, and the con- 

 struction of the object-glass much simplified, there being only ten surfaces and 

 but one concave of dense flint used in correcting four convex lenses of crown 

 glass. Mr. Wenham in planning an object-glass prefers constructing a diagram 

 on a large scale, as being far less intricate than mathematical calculation. 

 The paper is very fully illustrated, and will be duly appreciated by all 

 interested in the construction of objectives, as it forms an admirable sequel to 

 the valuable series of papers by the same author in the first volume of the 

 " Monthly Microscopical Journal." 



HEAT. 



Professor Wheildon, of Concord, U.S.A., advances, in opposition to what is 

 known as the Gulf Stream Theory, an atmospheric theory to account for 

 amelioration of climate and an open sea in the polar regions. The accounts 

 of Arctic voyages show sudden rises of temperature when nothing but an un- 

 limited extent of ice is near. These changes could not have been conse- 

 quences of proximity of open water, which at the highest, would only be 29 

 of temperature. The theory of Professor Wheildon is that open, melting ice, 

 rain after snow, and other phenomena in Arctic regions, are not caused by 

 winds warmed by an open sea, but by a circulation of air in which warm 

 winds descend from upper atmospheres ; being a circulation by which winds 

 heated at the equator reach the poles. 



Having occasion to cool a red-hot copper ball, Mr. W. F. Barrett plunged it 

 into a vessel of soapy water. The ball entered the water without any hissing 

 or perceptible evolution of steam ; and upon being removed seemed as brightly 

 incandescent as before ; other metal balls were then tried with the same result. 

 The soapy water was then replaced by fresh; but upon plunging an incan- 

 descent ball into this, the hissing was loud and the evolution of steam copious. 

 Mr. Barrett infers that the presence of soap in the water contributed to the 

 formation of the spheroidal state. Further observation showed also that 

 albumen, glycerine, and organic matters generally facilitated its occurrence. 

 The author seeks to establish a possible relationship between this phenomenon 

 and certain boiler explosions, from the possible entrance into boilers of oil or 

 other organic matter. 



The Earl of Rosse has communicated to the Royal Society a paper " On the 

 Radiation of Heat from the Moon, the Law of its Absorption by our Atmo- 

 sphere, and its variation in amount with her Phases," in which he gives an 

 account of a series of observations made in the Observatory of Birr Castle, in 

 further prosecution of a shorter and less carefully conducted investigation, as 

 regards many details, which forms the subject of two former communications 

 (" Proceedings of the Royal Society," vol. xvii., p. 436 ; xix., p. g) to the Royal 

 Society. The observations were first corrected for change of the moon's dis- 

 tance from the place of observation, and change of phase during the continu- 

 ance of each nighfs work, and thus a curve, whose ordinates represented the 

 scale-readings (corrected), and whose abscissas represented the corresponding 

 altitudes, was obtained for each night's work. By combining all these a single 

 curve, and table for reducing all the observations to the same zenith-distance 

 was obtained, which proved to be nearly, but not quite, the same as that found 



