THOMAS JEFFERSON IN RELATION TO BOTANY 35^
^t at Pittsburg, and am in hopes, that by jiourself or your friends, some attentiTe person there may be engaged to send them to you.
He continneB with characteristic ezplicitness :
They should come as fresh as possible, and come best, I believe, in a box of sand.
Nearly a year elapses hef ore he hears from Hopkinson who evidently is not clear that he has obtained the right thing and Jefferson replies to him from Paris, December 23, 1786. "The paccan nut is, as you con- jecture^ the Illinois nut. The former is the vulgar name south of the Potomac^ as also with the Indians and Spaniards^ and enters also into the botanical name^ which is Jttglans paccan/^ Here it will be noted he adopts Marshall's proposed name.
During the years spent in Paris, Jefferson was at the very heart of ^European activity and in the lack of newspapers he served as a reporter on the progress of science for some of his American friends as well as for Harvard, Tale, and perhaps other institutions. Among those to whom he frequently wrote on subjects of this nature was his good friend Bishop James Madison, the President of William and Mary Col- lege, at Williamsburg, Va. A letter written by him on July 19, 1788, at Paris wiU show how well Jefferson played the part of scientific scout for America.
Yon know also that I>r. Ingenhanss had discovered, as he supposed, from experiment, that vegetation might be promoted by occasioning streams of the electrical fluid to pass through a plant, and that other physicians had received and confirmed this theory. He now, however, retracts it, and finds by more de- cisive experiments, that the electrical fluid can neither retard nor forward vege- tation. Uncorrected stiU of the rage of drawing general conclusions from partial and equivocal observations, he hazards the opinion that light promotes vegetation. I have heretofore supposed from observation, that light affects the color of living bodies, whether vegetable or animal; but that either the one or the other receives nutriment from that fluid must be permitted to be doubted of, till better confirmed by observation.
The state of physics at that time is keenly illuminated by his re- marks on light as a fluid like electricity. How inadequate the view before the conceptions of energetics entered is shown by the remark concerning the non-nutritiousness of the light fluid.
Jefferson closes this letter with a little rather debatable philosophy
growing out of this ill fortune of the efforts of Ingenhauss.
It is always better to have no ideas than false ones; to believe nothing, than to believe what is wrong. In my mind, theories are more easily demolished than rebuilt.
Fortunately for Thomas Jefferson and for us, he was never able to rigidly follow this creed of skepticism. Of the truth of his obser- vation on the perishability of theories we can all bear him witness.
It may be of interest to note in passing that last year I f oimd among the remains of Jefferson's library now in the Library of Congress a copy of Ingenhauss's book entitled " Experiments on Vegetables.'*
In 1791 in company with his plant-loving friend Madison^ Jefferson
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