192 E. H. BOOTH. 
till its solar diameter is the same as that of the 16 foot 
camera, together with the corresponding plate from the 
latter instrument. 
The box camera records are not sufficiently sharp to be 
of any use for inner corona work—consequently tbey are 
being employed for outer corona measurements, including 
extreme recorded length of streamers. 
Another point of interest is the spreading of the exposures 
over the full time of totality—the moon moved approxi- 
mately from the western to the eastern edge of the sun, 
so naturally the prominences at the eastern limb could be 
photographed only immediately after second contact, and 
the prominences at the western limb only immediately 
before third contact. 
If allowed to repeat the performance, the following 
exposures and spacing would be adopted for inner corona 
photographs, f 64 :-— 



Plate No. | Exposure. | Time of commencement of Exposure. 
1 | 3seconds! 1 second after second contact. 
2 | Ly Wise ZO my oe : 7 5 
3 7: ee 1 minute ,, ie oie: 
A ODS ae 1 minute 40 seconds after second contact 
5 | RA eA | 35 seconds before third contact. 
6 BV ok LONER. ‘f < if 

This is, of course, counting on a totality of three and a 
half minutes—if shorter, plates 2 and 5 would be the first 
‘cut out. 
The Physical Laboratory, 
The University of Sydney. 

