On the Determination of the Orbits of Comets
According to the Methods of Father Boscovich and Mr de la Place

First published in 1793, this concise monograph is a valuable early manual for the computation of cometary movement.

Henry Englefield (Author)

9781108061735, Cambridge University Press

Paperback / softback, published 27 June 2013

290 pages, 4 b/w illus.
24.4 x 17 x 1.5 cm, 0.47 kg

When this book first appeared in 1793, there had been no significant work on comets published in English since Edmond Halley's death some fifty years before. In Europe the field was dominated by French astronomers such as Pingré and Laplace, but their ornate styles were often difficult to translate. In this concise monograph, Sir Henry Englefield (c.1752–1822) draws both on this continental work and on his own correspondence with William Herschel to produce one of the few accessible manuals in English for the computation of cometary orbits. He includes mathematical examples as new formulae are introduced, along with detailed tables and appendices. Englefield's particular interest was in the development of scientific instruments suitable for travellers - he devised a portable telescope and lent his name to the Englefield mountain barometer - and his passion for efficiency shines through in this work, still valuable to researchers in the history of astronomy and comet science.

Preface
1. General view of the method
2. On the motion of the point of intersection of the radius vector and cord
3. On the comparison of the parabolic cord with the space which answers to the mean velocity of the earth in the same time
4. Of the reduction of the second longitude of the comet
5. On the proportion of the three curtate distances of the comet from the earth
6. Of the graphical declination of the orbit of the earth
7. Of the numerical quantities to be prepared for the construction or computation of the comet's orbit
8. Determination of the distances of the comet from the earth and the sun
9. Determination of the elements of the orbit from the determined distances
10. Determination of the place of the comet from the earth and sun
11. Determination of the distances of the comet from the earth and sun
12. Determination of the comet's orbit
13. Determination of the place of the comet
14. Application of the graphical method to the comet of 1769
15. Application of the distances found
16. Determination of the place of the comet, for another given time
17. Application of the trigonometrical method to the comet of 1769
18. Determination of the elements of the orbit of the comet of 1769
Example of the graphical operation for the orbit of the comet of 1769
Example of the trigonometrical operation for the orbit of the comet of 1769
Conclusion
La Place's general method for determining the orbits of comets
Determination of the two elements of the orbit
Application of La Place's method of finding the approximate perihelion distance
Application of La Place's method for correcting the orbit of a comet, to the comet of 1769
Explanation and use of the tables
Tables
Appendix
Plates.

Subject Areas: Astronomy, space & time [PG]