David Alter was an American iscientist, physician and inventor. He was the discoverer of the principles of the prism in spectrum analysis.
Background
David Alter was born on December 3, 1807 in Westmoreland, Pennsylvania, United States. He was a grandson of Johan Jacob Alter, who came to America on the Beulah, from Amsterdam, in 1753, immediately took the oath of allegiance to Pennsylvania, and during the Revolutionary War served with a Pennsylvania regiment. John Alter, the father of David, was born in 1771 and in 1800 moved to Westmoreland County in western Pennsylvania. David's mother was Helenor Sheetz, of Swiss descent, whose grandfather had come to America in 1740.
Education
Alter's early formal schooling was poor, but a life of Benjamin Franklin, given him when nine, and a little later a book on electricity, supplemented by a few simple electrical devices, seem to have shown him very early where his chief interest was to lie. When twenty-one, he entered the Reformed Medical College in New York City, graduating three years later.
Career
In 1836 Alter invented a telegraph, which seemed to have been among the first successfully used, consisted of seven wires, each deflecting a needle. Combinations of deflections spelled the messages. Although it was in actual use between his house and barn, a patent was apparently refused on the ground that such an invention was absurd. Claims have been made that this was the first telegraph, but another, likewise not used commercially, seems to have been invented in Alabama in 1828.
A controversy has raged over Alter's discoveries in spectrum analysis. It is certain that far more credit is due him than was at first generally recognized, but, on the other hand, the assertion that he anticipated Kirchhoff's greatest discovery is without foundation. The fundamental principles of spectrum analysis are grouped in three laws commonly called Kirchhoff's Laws. The first of these had been common property for years.
Alter and the great European physicist Angstrom independently and almost simultaneously discovered and published the second, i. e. , that the various elemental gases have spectra peculiar to themselves. This law made possible the determination of the chemical nature of gases by means of the spectroscope and was an extremely important advance.
The third of Kirchhoff's laws, that of absorption spectra, while it is the most important of the three, was not known either to Angstrom or to Alter. It is unfortunate that at least two biographers have made charges of theft against Kirchhoff. Certainly Alter made no such charges.
Achievements
Throughout his life Alter devoted himself to physical experiments, showing remarkable ability despite the handicaps of his position, his apparatus even to prisms and lenses being almost entirely home-made. Among many minor inventions and discoveries were a successful electric clock, a method of purifying bromine, and the model of an electric locomotive. More important, however, were an electrical telegraph, early discoveries in spectrum analysis, and a method of obtaining coal-oil from coal; the last was apparently the only project which he considered commercially, and its chances of enriching him were destroyed by the drilling of the first Pennsylvania oil-well.
Connections
Alter was twice married: first in 1832 to Laura Rowley, and in 1844 to Elizabeth A. Rowley. There were eleven children by these two marriages.
