# American Horological Journal, Vol. I, No. 1, July 1869: Devoted to Pratical Horology

Author: Miller, George B. [Editor]

Genre: Category: Science - Physics

Language: English

License: Public domain

Source: https://www.gutenberg.org/ebooks/67859

Amazon editions: https://www.amazon.com/s?k=American+Horological+Journal%2C+Vol.+I%2C+No.+1%2C+July+1869%3A+Devoted+to+Pratical+Horology+Miller&tag=cyberlibrar00-20

## Summary

However accurate an instrument for the mensuration of time may be, it would be of little use for close observation unless we have some standard by which to test its performance. We look to Astronomy to furnish us with this desideratum, nor do we look in vain. The mean sidereal day, measured by the time elapsed between any two consecutive transits of any star at the same meridian, and the mean sidereal year--which is the time included between two consecutive returns of the sun to the same star--are immutable units with which all great periods of time are compared; the oscillations of an isochronous pendulum affording us a means of correctly dividing the intermediate space into hours and days.

## Chapters

- [Part 4](https://www.cyberlibrary.org/en/books/american-horological-journal-vol-i-no-1-july-1869-devoted-to-pr-223e4470/chapters/4/index.md)
- [Part 3](https://www.cyberlibrary.org/en/books/american-horological-journal-vol-i-no-1-july-1869-devoted-to-pr-223e4470/chapters/3/index.md)
- [Part 1](https://www.cyberlibrary.org/en/books/american-horological-journal-vol-i-no-1-july-1869-devoted-to-pr-223e4470/chapters/1/index.md)
- [Part 2](https://www.cyberlibrary.org/en/books/american-horological-journal-vol-i-no-1-july-1869-devoted-to-pr-223e4470/chapters/2/index.md)
- [Part 5](https://www.cyberlibrary.org/en/books/american-horological-journal-vol-i-no-1-july-1869-devoted-to-pr-223e4470/chapters/5/index.md)