INTRODUCTION. 



THE first occasion, I believe, in late years, on which the attention of the 

 British public was pointedly called to the approaching Transits of Venus, was 

 ray communication to the Royal Astronomical Society, dated 1857, April 8, 

 " On the means which will be available for correcting the measure of the 

 Sun's distance in the next 25 years." This paper was not limited to the 

 consideration of Transits of Venus, a part of it being devoted to the Oppo- 

 sitions of Mars. Much attention, however, was given to the selection of 

 stations for observation of the Transits both of 1874 and of 1882. 



On 1864, May 5, I addressed another communication to the same body, 

 relating only to the Transit of 1882, and to the necessity for a reconnoissance 

 of antarctic countries if an observation with the Sun below the pole should be 

 contemplated. 



On 1868, October 10, I began a correspondence with the Hydrographer, 

 Captain (now Sir George) Richards, on the general subject. 



On 1868, December 11,1 read a communication to the Royal Astronomical 

 Society, " On the Preparatory Arrangements which will be necessary for 

 efficient observation of the Transits of Venus in the years 1874 and 1882." 

 This paper was accompanied with eight maps of the regions which appeared 

 proper for the observations of. Ingress and Egress, accelerated and retarded 

 by Parallax, in the two Transits. An active discussion followed, in which the 

 Hydrographer and several Navy Officers took a prominent part. 



On 1869, February 15, I sent certain papers to the Secretary of the 

 Admiralty ; on April 9 I wrote more formally with Estimate of Expense of 

 Instruments ; and on May 25 I sent a printed copy of the discussion of 

 1868, December 11, including also a paper by Mr. De La Rue on the 

 application of Photography. About the same time an Estimate was 

 furnished by the Hydrographer for expenses of travelling, residences, &c. 

 [Each of these estimates proved ultimately much too small, the deficiency of 

 my own being mainly in respect of observing-huts and general packages.] 

 Approval to a certain extent was given by the Admiralty, and instrumental 

 and other preparations were begun. Those transactions were reported to the 

 House of Commons on July 6. 



Q ni. wt. 17091. a 2 



M761607 



