THE STARS. 151 



worn out and unfit for use had revealed 

 parallaxes in Sirius, Aldebaran, Procyon, and 

 Vega ; Calandrelli, another Italian, and John 

 Brinkley (1763-1835), Astronomer-Royal of Ire- 

 land, were similarly deluded; and in 1821 it was 

 shown by Friedrich Georg Wilhelm Struve (1793- 

 1864), the great German astronomer, that no 

 instruments then in use could possibly be suc- 

 cessful in measuring the stellar parallax. A few 

 years later, however, Fraunhofer brought the 

 refractor to a degree of perfection surpassing all 

 previous efforts. In 1829 he mounted for the ob- 

 servatory at Konigsberg a heliometer, the object- 

 glass of which was divided in two, and capable 

 of very accurate measurements. This heliometer 

 eventually revealed the parallax of the stars in 

 the able hands of Friedrich Wilhelm Bessel. 



Friedrich Wilhelm Bessel was born at Minden, 

 on the Weser, south-west of Hanover, on July 

 22, 1784. His father was an obscure Govern- 

 ment official, unable to provide a university 

 education for his son. Bessel's love of figures, 

 together with an aversion to Latin, led him 

 to pursue a commercial career. At the age of 

 fourteen, therefore, he entered as an apprenticed 

 clerk the business of Kuhlenkamp & Sons, in 

 Bremen. He was not content, however, to 

 remain in that humble position. His great 



