PROFESSOR PIAZZI SMYTH ON COMETARY PHYSICS. 145 







be little doubt, from the pressing nature of the demand for advance in this depart- 
ment, that those who are more fortunately situated, must, before long, perfect 
and employ some method by which the great desideratum for inquiry into cometary 
physics may be obtained, viz., drawings, wherein every feature represented shall 
be accompanied by numerical statements of its dimensions and brightness, with 
- the probable error of each determination. Until this shall have been done, the 
necessary corrections to reduce the apparent to the real phenomena cannot be 
undertaken, and { shall therefore hope to return to the subject if it should not be 
taken up in the meantime by any one better able to conduct it to a successful 
issue. 
