# Popular Science Monthly/Volume 11/July 1877/Dr. Balfour Stewart

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BALFOUR STEWART
* DR. BALFOUR STEWART.
AMONG English physicists Dr. Balfour Stewart holds a distinguished place for the originality and extent of his experimental researches, the grasp of his subtile and comprehensive inquiries, and the boldness and freedom of many of his speculations.
He was the son of a merchant, and was born in Edinburgh, November 1, 1828. At the age of fourteen he went to the University of St. Andrews, and afterward to that of Edinburgh, from which he graduated. During his college course he paid a great deal of attention to pure mathematics, and is credited with having rediscovered, independently of books, La Grange's method of dealing with the differential calculus. After leaving college he spent four years in a mercantile house, and was for two or three years in Australia; but his father's preference that he should be a merchant did not coincide with his own inclinations, and he at length determined to devote his life to physical science.
On his return from Australia, he was so fortunate as to secure the friendship of the late Principal Forbes, and became his assistant in Edinburgh for three years, 1856-'57-'58.
Dr. Stewart has been Director of the Magnetic Observatory at Kew, where he has made numerous and important magnetical observations in connection with the eminent physicist, Mr. Warren De la Rue. He is Professor of Physics in Owens College, Manchester, a Fellow of the Royal Society of Great Britain, of the Astronomical and Meteorological Societies of London, and of various learned bodies on the Continent and in the United States. He received the degree of LL. D. from Edinburgh University, and in 1868 the Rumford Medal of the Royal Society for his researches in light and heat.
Dr. Stewart has been a very active worker in the scientific field, and is the author of many publications, especially in the branches of meteorology, magnetism, and solar physics, of which the following are the most important:
Papers connected with Heat and Light.—1. An Account of Some Experiments on Radiant Heat, involving an Extension of Prevost's Theory of Exchanges (Transactions of Royal Society, Edinburgh, 1858). 2. Researches on Radiant Heat, Second Series (Transactions of Royal Society, Edinburgh, 1859). 3. On the Light radiated by Heated Bodies (Proceedings of Royal Society, London, 1860). 4. On the Nature of the Light emitted by Heated Tourmaline (Proceedings of Royal Society, London, 1860). 5. Internal Radiation in Uniaxal Crystals (Proceedings of Royal Society, London, 1861). 6. Report on the Theory of Exchanges (British Association, 1862).
Papers connected with Meteorology, Magnetism and Sun-spots.​—1. On an Instrument for measuring Fluctuations of Temperature (Proceedings of Royal Society, London, 1856). 2. Reduction of Makerstown Magnetical and Meteorological Observations, from 1847 to 1855 (Transactions of Royal Society, Edinburgh, 1860). 3. On the Magnetical Survey of Scotland undertaken by the late Mr. Welsh (Report of British Association, 1859). 4. An Account of the Self-recording Magnetographs erected at the Kew Observatory by the late Mr. Welsh (Report of British Association, 1859). 5. On the Great Magnetic Disturbance, August to September, 1859 (Transactions of Royal Society, London, 1861). 6. On the Nature of the Forces concerned in producing the Greater Magnetic Disturbances (Transactions of Royal Society, London, 1862). 7. A Comparison of the Kew Curves with the Earth-Currents registered at Greenwich during the Magnetic Storm of December 14, 1862 (Proceedings of Royal Society, London, 1863). 8. On Earth-Currents during Magnetic Calms, and their Connection with Magnetic Changes (Transactions of Royal Society, Edinburgh, 1863). 9. An Account of Some Experiments with an Air-Thermometer (Transactions of Royal Society, London, 1863). 10. Results of a Comparison of Simultaneous Traces of Self-recording Magnetographs at Kew and Lisbon—in conjunction with Senhor Capello (Proceedings of Royal Society, London, 1864). 11. On the Sudden Squalls of October 30 and. November 21, 1863 (Proceedings of Royal Society, London, 1863). 12. Note on the Secular Change of Magnetic Dip at the Kew Observatory (Proceedings of Royal Society, London, 1866). 13. A Description of the Self-recording Instruments of the Meteorological Committee (Report of the Meteorological Committee for 1867). 14. A Comparison between the Records of the Barographs at Oxford and Kew (Proceedings of Royal Society, London, 1867). 15. An Account of Experiments on Aneroid Barometers (Proceedings of Royal Society, London, 1868). 16. On the Laws regulating Magnetic Peaks and Hollows (Proceedings of Royal Society, London, 1869). 17. Results of a Preliminary Comparison of the Kew and Stonyhurst Declination Curves—in conjunction with the Rev. W. Sedgreaves (Proceedings of Royal Society, London, 1869). 18. Remarks on Meteorological Reductions (British Association, 1869). 19. Results of Observations of Dip and Horizontal Force made at Kew from April, 1863, to April, 1869 (Proceedings of Royal Society, London, 1870). 20. On the Variations of the Daily Range of Atmospheric Temperature as recorded at the Kew Observatory (Proceedings of Royal Society, London, February, 1877). In this paper the author shows that in the daily range of temperature there is unmistakable reference to the moon. 21. On the Variations of the Daily Range of Magnetic Declination, as recorded at the Kew Observatory (Proceedings of Royal Society, London, 1877). In this paper Prof. Stewart establishes the opinions previously held by Mr. De la Rue, Mr. Loewy, and himself, clearly showing that in the variations of declination range at Kew ​there are inequalities having reference to planetary configurations. He also shows that there is a great likeness between meteorological and magnetical phenomena, and suggests that a further study of sunspots may ultimately enable us to predict longer and longer meteorological occurrences.
Papers on the Heating of a Disk by Rapid Rotation in Vacuo.—1. On the Heating of a Disk by Rotation in Vacuo—in conjunction with Prof. Tait (Proceedings of Royal Society, London, 1865). 2. On the same subject—in conjunction with Prof. Tait (Proceedings of Royal Society, London, 1866). 3. On the same subject—in conjunction with Prof. Tait (Proceedings of Royal Society, London, 1873). 4. (A Possible Explanation of its Effect?) On the Temperature Equilibrium of an Inclosure containing a Body in Visible Motion (Literary and Philosophical Society, Manchester, November, 1870). Dr. Stewart endeavors to explain the heating of a disk of rotation in vacuo by an extension of the theory of exchanges.
Papers on Solar Physics by Messrs. Warren De la Rue, B. Stewart, and B. Loewy (Preliminary Researches—printed for private circulation by Mr. De la Rue). First Series: On the Nature of Sun-spots (1865). Second Series: Area Measurements of Carrington Observatory, and Deductions therefrom (1866). Third Series: On the Distribution of Spots in Heliographic Latitude.
Kew Researches.—1. Heliographic Positions and Areas of Sunspots observed with the Photoheliograph during the Years 1862 and 1863 (Transactions of Royal Society, London, 1869). 2. Positions and Areas of Sun-spots observed at Kew during the Three Years 1864-'66, as well as Fortnightly Values of Spotted Solar Area from 1832 to 1868 (Transactions of Royal Society, London, 1870). 3. On Some Recent Researches in Solar Physics, and a Law regulating the Time of Duration of the Sun-spot Period (Proceedings of Royal Society, London, 1871). 4. Further Investigations on Planetary Influence upon Solar Activity (Proceedings of Royal Society, London, 1872). 5. On a Tendency observed in Sun-spots to change alternately from the one Solar Hemisphere to the other (Proceedings of Royal Society, London, 1873).
Besides various miscellaneous papers, not mentioned here. Dr. Stewart is the author of the following works:
An Elementary Treatise on Heat; Lessons in Elementary Physics; Conservation of Energy ("International Scientific Series"); and The Unseen Universe (in conjunction with Prof. Tait).