AT THE PHYSICO-TECHNICAL INSTITUTE 437 



he requires for one problem, in which a single indivisible 

 heavy particle moves under the influence of known forces, 

 unalterably distributed in space. He will reply that he requires 

 three. Their value is expressed in the measurements by which 

 he has determined the initial and final position of the particle, 

 and by the energy which it possessed in the first moment of 

 its motion. 



'If, however, there are ten such heavy particles exerting 

 reciprocal force upon each other, he will have to calculate thirty 

 integration constants that is, he has to discover how these 

 constant and (during the further undisturbed course of the 

 motion) unalterable values are constructed and calculated 

 from spatial measurements. 



' In the case of smaller groups, formed from natural bodies, 

 with reciprocal interaction, perturbations from without, which 

 alter the course of the motion, will be more frequent. But the 

 general form of the solution remains the same, even if the cal- 

 culations prove impossible for the human intellect, and for the 

 resources of our present mathematics, which is unable even to 

 construct the nine integration constants for three heavy particles. 



' We must, however, conclude from these considerations, that 

 these magnitudes, which can neither be destroyed nor added 

 to . . .' 



On December 14 a Memorial Ceremony was held in the 

 Singakademie at Berlin at the instigation of the Physical and 

 Physiological Societies. The Emperor, the Empress, and the 

 Empress Frederick, with the nearest relatives of the deceased, as 

 well as a large and distinguished assembly, were present at the 

 ceremony. As an introduction to the whole, the Choir of the 

 Kdnigliche Hochschnle fur Musik performed a chorale under 

 the direction of Professor Adolf Schulze. Then followed 

 a solemn discourse, delivered by his friend and colleague 

 of many years, Wilhelm von Bezold. Immediately after its 

 conclusion Joachim played Schumann's Abendlied, with organ 

 accompaniment, to which the departed had so often listened with 

 emotion. Another chorale terminated the solemn service. 

 Once more the Master was vividly recalled to the inward vision 

 of all who were present. ' His contemporaries and successors,' 

 says du Bois-Reymond (whose pen was to the last devoted to 



