I30 



SCIENCE. 



[Vol. XIII. No. 315 



LETTERS TO THE EDITOR. 



*,' Correspondents are requested to be as brief as possible. The writer's name is 

 in all cases required as proof of good faith. 



Twenty copies of the number containing his communication will be furnished 

 free to any correspondent on request. 



The editor will be glad to publish any queries consonant with the character of 

 the journal. 



Tornadoes: Fact vs. Fiction. 



There is no subject in meteorology of more absorbing interest 

 "than tliis. As our knowledge of the environment of tornadoes in- 

 creases, there must necessarily be modifications in our views of their 

 origin. One of the more recent and most significant of these 

 changes has been thetransferrenceof the cool northerly wind, meet- 

 ing the warm south wind, from the earth's surface to the upper 

 regions, where it is said to overflow the lower current, and produce 

 an unstable equilibrium in the atmosphere. It would seem as 

 though no subject can demand, more strongly than this, a solid 

 substratum of fact ; and yet, strange to say, the theories and specu- 

 lations about these terrible visitors have been far more extensive 

 than the facts. This seems a favorable time to state a few of the 

 more prominent facts and seeming fictions. The facts are these : — 



1. It has been well said that the most important recent develop- 

 ment has been the fact that tornadoes occur, not at the centre of 

 a general storm, but about four hundred miles to the south-east. 

 This fact was known fifteen years ago, but was first strongly em- 

 phasized in March, 1884. 



2. All currents in this region, even up to a great height, are from 

 the south before the tornado, as is well known from observations of 

 the upper clouds. 



3. The tornado invariably moves to the north-east ; and if, as 

 some believe, it takes its motion in the upper current, that must be 

 from the south-west, and cannot be from the north even after the 

 tornado. 



4. The pressure rises in a tornado, as has been observed a few 

 times in it, and it invariably rises at the centre of a thunder-storm, 

 ■which frequently develops into a tornado. 



5. That some other force than a violent gale blowing into a par- 

 tial vacuum is concerned in the destruction, is well shown by the 

 fact, that of two free barrels side by side, one of which was empty 

 and the other full, the former was left undisturbed, while the other 

 was completely obliterated. Fowls have been stripped of their 

 feathers, and people deprived of their clothing, which could not be 

 brought to pass by the most violent gale. 



6. The tornado is extremely sudden, and, advancing without any 

 warning, it interjects itself into a region of gentle southerly winds. 

 After it has passed, the southerly wind almost at once again predomi- 

 nates. The whole appearance is as though a disturbance, largely 

 having its own source of energy, had suddenly projected itself into 

 a quiet air, and passed on without bringing about any but a mo- 

 mentary change. 



7. Its velocity is nearly double that of the accompanying general 

 storm. 



8. Numerous thunder and hail storms are an invariable accom- 

 paniment. 



A few fictions are the following : — 



1. Professor Ferrel states on p. 327, "Recent Advances in 

 Meteorology," that in the tornado there is an unstable equilibrium 

 due to " the large vertical gradient of tenriperature decreasing with 

 increase of altitude." 



2. Mr. Finley, in Science of Feb. I, thinks that this same condi- 

 tion must be found, not in the tornado, but in the region just 

 around it. 



3. This abnormal decrease of temperature is due to cold air 

 overrunning warm. This is really an impossible condition, since 

 the denser cool air must always underrun that which is lighter and 

 warmer. That a most extraordinary decrease of temperature and 

 most extreme unstable equilibrium, possibly five hundred times as 

 great as can ever occur under natural conditions, does not pro- 

 duce a destructive whirl, advancing scores of miles from its origin, 

 is well shown by the seas of fire extending many square miles in 

 forest clearings. Here there is a temperature at least 1000" higher 

 than that of the air two or three hundred feet above it. There are 



occasional whirls set up over such a fire, but they are short-lived, 

 and extend only to its edge. 



4. There is a violent uprush of air at the tornado centre. As we 

 have just seen, the tornado is not at the storm-centre, but four 

 hundred miles to the south-east, where there is no rising tendency 

 in the air. 



5. There is a uniform flow of northerly upper currents over an 

 extended region, and tornadoes are produced at spots one hundred' 

 miles apart by the breaking-through of the warm lower air. 



6. The tornado, in its onward motion dipping here and there for 

 one hundred miles and more, has its energy kept up by a continual 

 upsetting of the equilibrium, conveniently occurring just in front of 

 it exactly at the moment of its advance, and nowhere else. These 

 latter certainly have no facts to sustain them, and must be regarded 

 as impossible or highly visionary till observations in the cloud 

 region give still further facts. Until these facts are had, it is un- 

 safe to theorize. H. A. Hazen. 



Washington, Feb. 4. 



A Deadly Gas-Spring in the Yellowstone Park. 



The familiar fable of the upas-tree, living in a valley of death 

 wherein all life was killed by its deadly exhalations and the ground 

 was strewn with the bones of its victims, has been proven, like 

 many a traveller's tale, to be a highly colored and exaggerated ac- 

 count of a natural phenomenon. The upas-tree is now well known 

 to have poisonous sap, but not poisonous vapors. But the story 

 survives in the accounts given of the Death Valley of Java, which 

 it was long believed no traveller could cross, " wherein every living 

 being which penetrated the valley falls down dead, and the soil is 

 covered with the carcasses of tigers, deer, birds, and even the bones 

 of men, all killed by the abundant exhalations of carbonic-acid gas, 

 with which the bottom of the valley is filled." Such is the descrip- 

 tion given by Lyell ' of this famous valley ; while another locality 

 is described as a place where " the sulphurous exhalations have 

 killed tigers, birds, and innumerable insects, and the soft parts of 

 these animals are perfectly preserved, while the bones are eroded 

 and entirely destroyed. The researches of Junghuhn • have shown 

 that these accounts are much exaggerated, the " valley of death " 

 being a funnel-shaped depression but one hundred feet in diameter, 

 instead of a valley half a mile across. In the bottom of this de- 

 pression there is a hole about fifteen feet in diameter, from which 

 gaseous emanations are given out, which at times accumulate to a 

 depth sufficient to envelop and suffocate animals on the bottom of 

 the hollow. Repeated visits by Junghuhn, extending over a period 

 of twelve years, showed that the amount of gas varied greatly from 

 time to time, but rarely ever rose over two feet and a half above the 

 bottom. At the time of his earlier visit, he found the body of a 

 Javanese native in the depression, but experienced no difficulty or 

 oppression while there himself. This same body was still unde- 

 composed, owing to the preservative effect of the layer of gas, 

 when he repeated his visit eighteen months later. The only other 

 remains seen during his subsequent visits were the carcasses of six 

 swine which were decomposed and putrid. At this time the ab- 

 sence of the gas was shown by the presence of a crow feeding up- 

 on the dead bodies. 



Though thus shorn of much of its former glory, this Pakaraman, 

 or poison-hole, is the largest and most dangerous of the gas- springs 

 or mofettes of Java, and indeed of the world, and really deserves 

 the title of a natural death-trap. Though such emanations are 

 common in all volcanic regions, this has been the only place known 

 where the gases have accumulated, and caused the death of the 

 larger animals. 



In the Yellowstone National Park, now so well known as the 

 wonderland of America, there is a place equalling this famous 

 death valley, and where the gaseous exhalations have proved fatal 

 to numerous bear, elk, and many smaller animals. 



This place, to which the appropriate name of " Death Gulch " is 

 given, was discovered by the writer during the past summer (1888), 

 while making a geological examination of the region for Mr. Arnold 

 Hague, the geologist in charge of the survey of the park. It is- 

 situated in the extreme north-eastern portion of this reservation, a 



Principle 

 Java Sei. 



of Geology, 1878, i. p. 590. 



; Gestalt, etc., German translation by Hass Karl, ii. p. 



