April 14, 1893.] 



SCIENCE. 



205 



The date of this abnormal heat was Deo. 31, 1883.' Another 

 •occasion was on Nov. 18, 1885, and a third on Feb. 5, 1886. These 

 are the only marked cases from December, 1883, to February, 

 1886, though there were minor cases of no importance on Jan. 16 

 and Dec. 33, 1884, and on Nov. 10, 1885. I have made a careful 

 search of all the published observations for maximum barometer 

 readings in the four cold months, and have found 70 cases. That 

 is to say, out of 70 cases, only 3 show a marked departure from 

 the law that there is the same oscillation of temperature at the 

 summit as at the base of Ben Nevis. But this is not all. On 

 Dec. 31, 1883, the motion of the high area was quite slow and the 

 wind on Ben Nevis almost a calm, thus causing a stagnant air. 

 On Dec. 38, or three days earlier, the temperature at the summit 

 began falling, and in 24 hours it had fallen nearly 22° F., or more 

 than at the base in the same time. This shows that the usual 

 law was acting even in this case and that the subsequent rise was 

 due to an abnormal condition and not to the fact that the tem- 

 perature was higher in the centre of the high area than on either 

 side. 



In the other case cited by Dr. Hann on Nov. 18, 1885, the con- 

 ditions were exceedingly abnormal, as the high area moved from 

 the east toward the west. It would be impossible to reason as to 

 the ordinary temperature conditions in a high area from such a 

 case. It is an interesting fact that in the latter case the oscilla- 

 tion of temperature at the summit was precisely the same as at 

 the base, except that the fall and rise at the summit was a little 

 greater than at the base, and it took place about 24 hours later, 

 instead of earlier as is usually the case. The usual law of lower 

 temperature in the centre of a high area is abundantly borne out 

 at Ben Nevis, and I have found the reverse law in the centre of a 

 liiw area also true at that station. 



I have thus dwelt at some length upon these studies for the 

 reason that they have been largely accepted by European meteor- 

 ologists and have served to overthrow nearly every hypothesis 

 that has been regarded invulnerable in the past. Is there not 

 hero the best proof in the world of the extreme need of an ex- 

 ploration of the atmosphere at the seat of these disturbances? 

 Meteorology needs, above all things else just at present, a full 

 and complete setting forth of the facts to be gleaned in the upper 

 atmosphere. An array and study of these facts would give us a 

 good foundation on which to lay the corner-stone of a good and 

 exact science. It would be of inestimable value in forecasting 

 the weather and in removing our ignorance, which is so serious a 

 drawback at present. 



We do not know positively the simplest conditions in the at- 

 mosphere. Glaisher once left London in a pouring rain and 

 emerged into clear sky after rising only 800 feet. At another 

 time be found rain falling in a cloud 15,000 feet high. In this 

 country no rain has been observed in balloon ascensions above 

 9,000 feet, and it is probable that a large part of our rain forms 

 at a height less than 6,000 feet. We do not know the thickness 

 of a rain-cloud nor its temperature. Some think the temperature 

 must be higher than that of the surrounding air, else the storm 

 would quickly cease; others think that no rain can form unless 

 the temperature is lower than the outside air. Our books are full 

 of speculations as to the dynamic heating of the air and the con- 

 ditions needed to originate and maintain our storms and high 

 areas. The evidence seems quite clear that all these theories, 

 often contradictory among themselves, would not account for a 

 tithe of the energy displayed, and an exploration is needed to de- 

 termine this fact, or to establish the truth. 



Is there an ascending current in our storms, or a descending one 

 in our high areas? These are theories of the deepest interest. 

 The evidence seems to show that there is not a transfer of an air- 

 mass in any direction, either up or down or horizontally, in our 

 storms or high areas. Professor R. H. Scott, after giving all 

 possible sources of rain formation, decides that the only one that 

 can be maintained on theoretical grounds is that rain is formed 

 in an ascending current of warm, moist air. A determination of 

 this question would be of inestimable value in all studies and re- 

 searches as to the natural or artificial formation of rain. 



» Misprtnted 1884. 



In several ascensions in this country it has been found that 

 there seem to be rather definite layers of moisture even in a clear 

 sky. Sometimes two layers have been found at different heights. 

 These would seem to be exceedingly significant facts. Do these 

 layers serve as conductors for electric currents, as seems to have 

 been very guardedly stated by Professor Loomis? How do these 

 layers thicken as a storm comes up, or, rather, is the thickening 

 process a precursor to the storm? Does this thickening in a cer- 

 tain definite direction show in what direction the storm will sub- 

 sequently move, or is it caused by the conditions accompanying 

 the storm? Do these layers rise or fall, or what is their move- 

 ment under different atmospheric conditions? 



What relation does the dust in the atmosphere bear to these 

 layers? Is there an increase of dust in definite layers? Is dust 

 needed to produce this thickening? It seems to me the careful 

 and painstaking investigations of Professor Barus in cloud con- 

 densation must bear valuable fruit as soon as he turns to the 

 ordinary conditions in our storms, and for this the study can be 

 prosecuted only with great difficulty, except in nature's own great 

 laboratory. 



A serious drawback in the past to successful balloon explora- 

 tion has lain in the lack of suitable instruments. Professor 

 Glaisher often took up instruments enough to stock a meteorologic 

 observatory, and in a single ascension once broke nearly $500 

 worth. What is needed is an instrument that can be read very 

 quickly, once a minute if possible, and, at the same time, do its 

 work very accurately. A sensitive aneroid will give the pressure, 

 and a sling psych rometer will give the moisture conditions. Vari- 

 ous rather singular objections have been raised to this instrument. 

 One is that it will give 5° too high temperature under strong inso- 

 lation. This experiment has been tried, and it is known that 

 under the strongest insolation possible the temperature will be 

 less than .8° higher in the sun than in the shade. Another objec- 

 tion raised has been that it will give a lower relative humidity in 

 bright sunshine than in shade. This is entirely wrong, because 

 the muslin coating of the wet bulb is a vastly better absorber of 

 heat than the bright bulb, and hence, if anything, in bright sun- 

 shine the relative humidity must be higher than in shade. It is 

 also said that the heat of the balloon will tend to raise the tem- 

 perature of the sling thermometer because it cannot be used far 

 enough away from the basket. In a comparison between the sling 

 thermometer and another so-called standard (aspiration thermo- 

 meter) the greatest difference between the two occuired when the 

 balloon was moving horizontally, and the least when the balloon 

 was ascending most rapidly, so that this objection utterly fails. 

 The true criterion of an accurate instrument is that it shall 

 give the same temperature of any stratum in a rapid ascent and 

 descent, and this is fulfilled in a marked degree by the sling psy- 

 chrometer. I have used this instrument for over eight years and 

 in five balloon voyages, and am satisfied that it is a perfect in- 

 strument and one that responds at once to any demands put 

 upon it. 



The expense of ballooning in the past has been enormous, and 

 a serious drawback to its prosecution. One is amazed to read 

 that in certain high ascensions, to five miles and over, the balloon 

 of 90,000 cubic feet capacity was filled plump full, thus necessi- 

 tating the carriage of about a ton and a half of ballast. This 

 ballast had to be poured out and more than half the gas wasted 

 before reaching the height desired. It is no wonder that the 

 aeronaut was completely exhausted with his labors with the ton 

 of ballast. All this gas that had to flow out, because of expan- 

 sion, was a dead loss, say, |150 for each ascension, and after land- 

 ing the remaining gas was emptied. All of this expense can be 

 avoided, as I am firmly convinced. It is well known that if a 

 balloon leaves the earth at all, it will rise till the envelope is 

 plump full. If the balloon will rise when two-fifths full of gas, 

 it will continue to do so till it has reached more than five miles, 

 the limit desii-ed at present, though there is no reason why ulti- 

 mately we may not ascend to the extreme limit to which hydro- 

 gen may carry us by the use of a pneumatic cabinet. It is pro- 

 posed to employ a small balloon with hydrogen gas. A balloon 

 of 20,000 or 30,000 cubic feet will easily carry two men when 

 half full, and the enormously less labor of handling it, as com- 



