H. Jacoby — Determination of the Division Errors, etc. 333 



Lord Salisbury, in his address before the British Association 

 at Oxford, 1894, remarks : " Oxygen constitutes the largest 

 portion of the solid and liquid substances of our planet, so far 

 as we know it ; and nitrogen is very far the predominant con- 

 stituent of our atmosphere. If the earth is a detached bit, 

 whirled off the mass, leaving the sun we cleaned him out so 

 completely of his nitrogen and oxygen that not a trace of these 

 gases remain behind to be discovered even by the sensitive 

 vision of the spectroscope ?" 



Although we have not succeeded in detecting oxygen in the 

 sun, it seems to me that the character of its light, the fact of 

 the combustion of carbon in its mass, the conditions for the 

 incandescence of the oxides of the rare earths which .exist, 

 would prevent the detection of oxygen in its uncombined 

 state. .Notwithstanding the negative evidence which I have 

 brought forward, I cannot help feeling strongly that oxygen is 

 present in the sun and that the sun's light is due to carbon 

 yapor in an atmosphere of oxygen. 



Jefferson Physical Laboratory. 



Akt. XXXIX. — On the Determination of the Division Errors 

 of a Straight Scale ; by Hakold Jacoby. 



1. Lying as it does at the base of all exact metrology, the 

 above problem has received the attention of many investigators. 

 Numerous methods have been devised and employed for its 

 solution, the object generally sought being a result of suffi- 

 cient accuracy accompanied with the minimum amount of 

 labor. Probably the first investigation in which the highest 

 precision was attained or even aimed at, was carried out by 

 Hansen.* His method amounts to comparing the spaces of the 

 scale under investigation, which we will call scale A, with a 

 series of spaces marked upon an auxiliary scale B. This was 

 done in such a way that every one-space of scale A was com- 

 pared with an auxiliary one-space ; every two-space of scale A, 

 with an auxiliary two-space, etc. The method may of course 

 be varied by using, instead of spaces on an auxiliary scale, a 

 fixed interval between the two microscopes of a comparateur. 

 In fact, Hansen's process really consisted in comparing inter se 

 all the single spaces, two-spaces, three-spaces, etc., of scale A. 

 The series of observations made in this way, Hansen treats by 

 the method of least squares, giving a solution whose numeri- 

 cal application requires a very considerable amount of compu- 

 tation. 



* Abh. d. math. phys. Classe der Kgl. Sachs, (resell, d. Wissenschaften, vol. xv. 



