THE COMING TRANSIT OF VENUS. 393 



methods, and it may be that this disagreement will render the final determination 

 far less satisfactory than it would have been if the several parties had acted in 

 concert. 



While the astronomers are using all the refinements of science to make their 

 observations as accurate as possible, it may be that some people who are not fol- 

 lowing this special line of work and who, it may be, are not particularly interest- 

 ed in the advancement of science, will find an interest in watching a transaction 

 that cannot occur again before the expiration of one hundred and twenty years. 

 Unfortunately, these random observations cannot be of use in making the final 

 determination of the distance of the Sun more accurate, but there is, neverthe- 

 less, a feeling of interest in knowing that one is looking sunward in common 

 with a large part of the civilized world. Adapting the data given in the Ameri- 

 can Ephemeris to the latitude and longitude of the University Observatory at Law- 

 rence, the times of the four principal phases of the transit are found to be as fol- 

 lows, expressed in Lawrence mean time : 



Transit begins yh. 43m. A. M. 



Internal contact at ingress 8 3 " 



Internal contact at egress .1 28 P. M. 



Transit ends i 48 " 



We see that it will take Venus about twenty minutes to pass over the edge 

 of the Sun and that more than six hours will elapse between the beginning and 

 ending of the transit. To change these times so as to accommodate them to 

 other localities in Kansas and Missouri, the only difference to be allowed for is 

 that caused by a difference of longitude. Thus : the map gives a difference in 

 longitude of thirty-five minutes of arc between Lawrence and Kansas City, and 

 this means that the phases of the transit will occur a little more than two minutes 

 later by Kansas City mean time than by Lawrence mean time. For those places 

 using the time furnished by the A., T. & S. F. or K. P. Division R. R.'s, it 

 will be sufficient to add fourteen minutes to the times given above. 



And now some one may ask how to see it. A person provided with good 

 eyes and a uniformly smoked piece of glass can see the whole transit. Venus 

 will appear as a very small black dot on the surface of the Sun, and will appear 

 to have an exceedingly slow motion from east to west. If, however, a person 

 has a telescope or opera-glass, the observations can be made much more easily 

 and satisfactorily. To the eye end of the telescope, and about a foot from it, 

 fasten a piece of stiff white cardboard nine or ten inches square to serve as a 

 screen. This can be most easily done with pieces of stiff wire tied to the tele- 

 scope. Then fasten around the object end of the telescope a shield to protect 

 this screen from the direct rays of the Sun. Place the telescope on some con- 

 venient rest, point the telescope toward the Sun, and pull out the eye-piece (or 

 lengthen the tube) a little until the image of the Sun on the screen is distinct. 

 With this arrangement half a dozen persons can see the transit at once with com- 

 fort and without any danger of injury to the eye. It may be of service to know 



