Nipher — Gravitation in Gaseous Nebulm. 459 



Aet. L. — On Gravitation in Gaseous Nebulw ; by Feancis 



E. Niphee. 



This subject has received attention of late through the 

 work of Dr. See, who has rediscovered the law announced by 

 Ritter in 1878. According to Ritter, if R be the radius of a 

 spherical mass of gas of cosmieal dimensions, and T its tem- 

 perature, the product TR = constant. As Ritter announced, 

 the heat capacity of such a gravitating mass is negative. If 

 heat leaves the gas, it contracts and becomes warmer. Dr. 0. 

 M. Woodward has recently published a paper* in which he 

 deals with the conditions of equilibrium in such a mass, and he 

 deduced the equation for the mass of the central core of a 

 gravitating spherical nebula 



K 



Here C is the constant for the gas, and M is the mass 

 internal to any radius r. K is the gravitation constant and T 

 is the constant temperature of the mass. Woodward admits 

 that if such a mass could be contracted, its temperature would 

 rise, but he denies that gravitation is competent to contract the 

 gas, and even concludes that such a nebula cannot lose heat by 

 radiation. 



The present writer, in the succeeding number of the Trans- 

 actions, has shown that such contraction is possible ; and that 

 when T is made variable in the above formula, the value of 

 Ritter's constant is determined by that equation, in terms of 

 the gravitation constant, the constant for the gas, and the mass 

 M internal to r. 



This equation is then applied to a cosmieal mass of hydro- 

 gen. What must be the physical condition in order that a 

 central mass or core, having a radius equal to that of the sun, 

 should contain a mass equal to that of the sun. The condi- 

 tions of the problem determine r, C and M ; and K being 

 known, the value of T turns out to be 20,000,000 degrees cen- 

 tigrade. The pressure at the surface of this sphere is com- 

 puted, and it is found to be 3*706 XlO 14 dynes per square 

 centimeter, or 366,000,000 atmospheres. The average density 

 of the spherical mass, which is three times the density at the 

 surface of the hydrogen sun, is about 7 per cent less than the 

 average density of the sun itself. The pressure at a distance 

 of 92 million miles from the center of mass is found to be 

 about 0-4 of an atmosphere. 



* Trans. Acad, of Sci. of St. Louis, vol. ix, No. 3. 



