I IO CARNEGIE INSTITUTION 



R. A. S. LVii, p. 349) the Hues on which I feel sure a simple and 

 efficient photographic transit circle could be constructed. The 

 heavy work of the Astrographic Chart has compelled me to defer 

 any trial of this method, but having nearly completed our measures 

 we are now on the point of trying it, and possibly information as 

 to its success may be forthcoming at an early date. The " magni- 

 tude equation "is so troublesome for eye observations that I feel 

 sure we ought not to delay the introduction of photography into 

 meridian work any longer, and I feel confident of the success of the 

 method suggested. No new departure is contemplated beyond 

 mounting a mirror on pivots instead of providing a telescope, and this 

 should offer no difficulty — rather the contrary. But I am well aware 

 that no instrument is complete so long as it is only on paper. 



2, 3, 4, 5, and 7. I thoroughly agree with what is said and have 

 no special remarks to make. 



6. Double Stars. — The work of Mr. R. T. A. Innes at the Cape 

 Observatory should be remembered ; but Mr. Innes has recently 

 been appointed director of a new observatory where this work may 

 not be possible, since the first call on his energies will be from the 

 meteorological side. Compare what has already been said about the 

 non-astronomical calls on the attention of directors of southern ob- 

 servatories. 



Other Observations not Mentioned in the ' ' Statement. ' ' 



8. Planetary observations of position from the southern hemisphere 

 are in some ways as desirable as stellar. Sir David Gill has already 

 started observations which will supply several of these wants; but I 

 should like to draw attention to the fact that a series of observations 

 of the moon which would give good places throughout the lunation 

 during at least one year would certainly improve our knowledge of 

 the parallactic inequality; and for completeness we should have 

 series obtained at both northern and southern stations, unless a 

 series could be obtained from near the equator, as Madras or 

 Kodaikanal. The chief requisite is a fine climate, such that the 

 moon could be caught very near new moon and pretty continuously 

 in at least one or two months. 



There are various methods which might be used ; to give one 

 example, photographs might be taken with a telescope clamped for 

 the night (a) of the moon and (b) of stars preceding or follow- 

 ing by a known interval. These photographs could be measured 

 and discussed elsewhere if necessary. 



