MS 611-15

1908 Nov 30 Logic I. i. 11

surprise me very much if I were to learn what it was destined to be. I shall therefore make a science include, as its core the sub a burning subject upon which some group of men are today passionately exploring together with other subjects which they are better fitted to explore than other men and in which they or men whose researches demand much the same facilities as their own are taking a close interest or must in the near future take up. But it is evident notorious that men's scientific affiliations have don are more close and less close. This more and less is not, however, a smooth slope. On the contrary, it arises from a man's possessing today special facilities, mental or material, for advancing knowle the solution of special certain problems, but yet and possessing besides very good facilities, which may a

1908 Nov 30 Logic I.i. 12

few years hence be much improved for taking up other problems. Thus, an astronomer may possess a heliometer, an instrument that few astronomer's possess,-and along with that he may possess high skill in using it,-which is a still rarer possession; an since today there is no other way of ascertaining the distances of single fixed stars at all comparable to measuring their annual parallax with a heliometer, he may be devoted, to that special branch of astronomy which may be call measures parallaxes; Be for the knowledge of them is will be indispensible to solving the problem of the constitution of heavens, when his great grandchildren or their contemporaries find themselves in a condition to ascertain something positive about that. But the measurement of a parallax with a heliometer is the most expensive kind of measurement

1908 Nov 30 Logic I.i. 13

imaginable; so that it is by no means impossible that the helometrist may prefer another year to use the photographic method, especially if, like Prof. Hale and the Carnegie observers he has a miror of 175 feet focal length, so that a second of arc would measure over a fifth of a millimetre on his photographs. He would, thus transform himself into a photographic astronomer, and would naturally be drawn into other researches in sidereal astronomy. One more remark about my use of the word science ought to be made in this connection; though I shall not fully explain my explanation of this bit of my usage must be explained a little later. Astonomers have taught mankind many things; but they did not teach men that the moon goes through a series of changes every 29 1/2 days. On the contrary, this was one