FACTS AND FANCY CONCERNING COMETS. 29 



was to suffer because it would be on one side of the sun, while the large planets 

 on the opposite would so attract our world as to attract earthquakes, pestilence 

 and death. So dense was the ignorance of the alarmist, that he actually dia- 

 gramed Venus on the wrong side of a sun, in a position in which it would not 

 arrive for more than six months. June 19 came and was all serene, but we read 

 of some being rendered insane by these publications. And now it is sought 

 again to awaken fear by the formulation of predictions of appalling heat that is 

 to reach the earth, because the great comet that illuminated the circumpolar 

 heavens last summer passed perihelion at a point close to the sun. The scheme 

 to destroy mankind is that the comet on its return in 1897, will suffer sufficient 

 retardation in passing through the gases constituting the corona of the sun to 

 cause it to fall. Inconceivable heat will be generated from the arrested motion, 

 and waves of it will surge against the earth, literally burning humanity alive. 

 All such doctrines are without the slightest grounds in reason or scientific deduc- 

 tion, and the mystery is why any man pretending to astronomical or mathemati- 

 cal acquirements will print such dogmas. 



If we raise a mass weighing 772 pounds i foot, and then let it fall, the pre- 

 cise amount of power required to raise it will be restored, and will appear in the 

 form of heat, at the instant of impact of the mass on the earth. And, as has 

 been proven, the amount of heat generated is just enough to raise the tempera- 

 ture of I pound of water 1° F. But the heat evolved by the fall of 772 pounds 

 I foot is equal to that developed by the fall of !• pound 772 feet. A mass weigh- 

 ing I pound that has fallen 772 feet has motion sufficient to conserve heat enough 

 to heat I pound of water 1° ; or i pound of water falling 772 feet generates 1° 

 of heat throughout its mass. This is termed Joule's heat equivalent, and is a 

 valuable element of human knowledge. It is a postulate of recent science that 

 when one mode of force vanishes, another of equal intensity takes its place. 

 Force cannot be increased or diminished ; it is one of nature's constants. Motion 

 is a mode of energy, and, invariably, when it terminates, heat — another form of 

 force — appears. 



Now, what possibly can be of greater moment than to learn how much 

 motion is required to evolve 1° of heat. We know how great a weight, and how 

 much space ; but now comes the question, how rapid must be the motion ? The 

 velocity acquired by a falling body at any instant of its fall is equal to the square 

 root of the product of twice the force of gravity and the space fallen through. If 

 a body be let fall, it will be found by delicate instruments to be moving, at the 

 close of I second, with a velocity of 32.2078 feet per second. And this velocity 

 is an expression for the force of gravity exerted by the mass of the earth on bod- 

 ies near its surface. By the rule, 32.2078 multiplied by 2 equals 64.4156, and 

 this multiplied by 772 equals 49,729 feet, whose square root is 223. Of all num- 

 bers known to man for purposes of physical research, this 223 is the most im- 

 portant ; for we now know that i pound of matter moving with velocity of 223 

 feet per second generates heat enough, when its motion ends, to heat i pound of 

 water 1°. That is, this velocity represents i pound-degree of heat, or simply 1°, 



