We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
ASTRONOMICAL PHOTOGRAPHY 301
field decreases so rapidly upwards that it could not have any appreciable effect on the higher regions of the sun's atmosphere. If this interpretation is correct, it would appear impossible that any combination of sunspots can be responsible for the magnetic storms which occur on the earth.
In one series of Hale's photographs a large hydrogen flocculus is shown which appears to be on the point of being drawn into a sunspot. He, therefore, concludes that sunspots are centres of attraction, drawing toward them the hydrogen of the solar atmosphere.
This subject is of such great importance that another Tower Telescope is being constructed which will have a focal length of 150 feet, and a spectrograph of 75 feet focal length will be used in connexion with that telescope. By its aid it is hoped that spectra of much smaller sunspots will be examined, as a focal image of the sun 16 inches in diameter will be so obtained.
Photography of Stars. — The solution of other important astronomical problems has been attempted with the help of photography ; for example, the production of pictures of the stars.
The object of such pictures is the representation of the constellations, or the relative position of the stars. It always has been one of the principal objects of astronomy to determine the position of the fixed stars.
The photographic process is of great importance for this purpose, because it offers advantages in the facility of its application and correctness of its results. Many readers may inquire why so much trouble is taken to determine with the greatest accuracy the positions of thousands and millions of fixed stars. The answer is that the fixed stars are not stationary, as their name implies ; nothing is stationary in nature, and hence such study is never at an end. No doubt the fixed stars change their position so slowly that the builders of the