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so that there remained no time for further experiments in Holland. 

 The object glasses of Zeiss of the small spectrograph were found to 

 be in excellent order, this instrument had produced very fine spectral 

 photographs. In order to slide the photographic plate for this instru- 

 ment during the flash phenomenon I put the clock-work in order 

 which in Sumatra had served for the motion of the axis carrying 

 the four photographic cameras. I devised an arrangement which 

 let slip the cord, fastened to the plate-holder, with greater velocity 

 than had been required in Sumatra. 



As photographic plates I chose, after experiments for comparison 

 with four different kinds of Schleussner's plates, his "Sternwarte" 

 and "orthochromatic" plate. At the last moment I fortunately obtained 

 two kinds of plates of Cadett, known to be very good. 



Operations at the camp. Besides the mounting of the different 

 instruments, the operations at the camp included therefore also 

 several experiments, as: tests for comparison of the old and new 

 object glasses and tests of the German and English plates. 



Owing to a delay in the construction of the pier, and because 

 I had to take charge of two instruments, whereas according to the 

 original plan of the expedition each spectral apparatus would be 

 worked by a separate observer, and also owing to the continual 

 disturbances from the side of the public, these operations did not 

 get on at the desired speed, so that at the last moment a great 

 many things remained to be done and the necessary calmness, which 

 in America in 1900 and in Sumatra in 1901 so much contributed to 

 regular proceedings, was entirely wanting. 



After tests for comparison we chose for object glasses those of 

 Steinheil, and for plates the English ones, especially as the ortho- 

 chromatic plates gave a much more regular spectrum than the 

 German plates of the same kind. 



Assistance, so easily obtained at the previous expeditions was 

 difficult to get here. Though several weeks before we had asked 

 for it on all sides, a promise of assistance reached us only a feAV 

 days before the critical moment. Not much could be expected from 

 it, but I myself intended to work the small spectrograph with the 

 sliding plate-holder and I hoped that the very simple operations with 

 the large spectrograph would offer no difficulties. Joint rehearsals as 

 were held for days together in America and Sumatra were quite 

 out of the question owing to the above mentioned circumstances. 

 Yet, though all things were so different from what Ave might wish 

 them to be, I still hoped to obtain useful results. 



