EXPERIMENTS WITH BALLOONS. 55 



which those related to British colonies occupied the chief place. Dr. Hodg- 

 kin observed, that the objects pursued by this Society furnished subject- 

 matter not merely for the Zoological, but also for the Medical and the Sta- 

 tistical Sections. Details of the plans, operations and present state of the 

 Aborigines' Protection Society may be obtained from its publications, which 

 are to be had at the Society's Office, 17 Beaufort Buildings, Strand. The 

 Queries regarding the races of man, to which this report refers, will be found 

 in another part of this volume. 



Report of the Committee appointed to report how far the Desiderata in our 

 knowledge of the Condition of the Upper Strata of the Atmosphere may be 

 supplied by means of Ascents in Balloons or othertvise, to ascertain the 

 probable Expense of such Experiments, and to draw up Directions for Ob- 

 servers in such circumstances. 

 Although much valuable information might be obtained by means of 

 aerostatic observation, the pecuniary outlay which would be required for 

 this purpose is so considerable, that the Committee do not at present recom- 

 mend any application of the funds for this object, much less any attempt to 

 induce Her Majesty's Government to incur the expense, until the plan has 

 been more fully matured. But experience derived from ascents made under 

 ordinary circumstances, as opportunity may offer, would be desirable, both 

 as regards the kind of instruments, the mode of using them, the special 

 points to be attended to, the degree of concordance to be expected in results 

 obtained at diiferent times, places, and states of the atmosphere. The prin- 

 cipal objects required are, to determine the progression of temperature, and 

 the law of the distribution of vapour, in ascending from the surface of the 

 earth to the upper regions of the atmosphere. There can be no doubt that, 

 in a perfectly dry and undisturbed atmosphere of air, the temperature would 

 be found to decrease as we ascend, as the density decreases ; and that this 

 must be its normal state to which, amongst all its fluctuations, it must tend. 

 The decrease of density, however, is liable to the action of various disturbing 

 causes, the principal of which are the evolution of heat by the local conden- 

 sation of vapour, and its absorption by the evaporation of clouds. The law 

 of the decrease would most probably be elicited from the mean results of a 

 great number of careful observations, in which a compensation of such dis- 

 turbances Avould take place; but it cannot be expected that it should be 

 apparent in such a limited series as can be comprised in a single ascent. It 

 is probable that the temperature observed at short intervals, instead of pre- 

 senting a regularly decreasing progression, would exhibit great irregularities ; 

 as, for instance, that it would be found in a calm to decrease to a certain 

 point, then become steady for a time, or possibly rise, especially upon passing 

 through a cloud, or upon entering a current flowing in a different direction 

 from that upon the surface : or, if the condensation of vapour were taking 

 place from the action of a cold wind flowing into, and mingling with, a 

 saturated atmosphere, instead of arising from the regular decrease of tem- 

 perature due to the decreased density, a sudden and great depression would 

 be found. The observer's attention should be particularly directed to the 

 influence of clouds or changes of currents upon the thermometer. Mr. Green 

 has found that the isothermal planes are parallel, or nearly so, to the earth's 

 surface, so that the aeronaut knows generally, even although the earth may 

 be intercepted by a cloud, when he is crossing a chain of hills ; or at least 

 the upper surface of the clouds generally follows in a great measure the con- 

 figuration of the earth. " The upper surface of the clouds, upon occasions 



