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FA R M EMS ' R E G I S T E R . 



Vor.. VI L 



NOVEMBER 30, 1839. 



No. 11. 



EDMUND RUFFIN, EDITOR AND PROPRIETOR. 



''-•'. For the Farmers' Register. 



ESSAY ON VEGETABLE PHYSIOLOGY. 



(Concluded from page 626.) 



By George D. ARMSTRONa, Prof. o( Nat. Philosophy 

 and Chemistry, Washington College, Va. 



Chap. XXllI. 

 I 



REMARKS ON THE APPLICATION OF SCIEN- 

 TIFIC PRINCIPLKSTO PRACTICAL, PURPOSES. 

 PROPER CHARACTER OF EXPERIMEM TS. 

 SOME EXAMPLES. 



In the preceding chapters of this essay, I have 

 endeavored to set before the reader, the principles 

 of vegetable physiology, together with the evi- 

 dence on which they rest ; and occasionally I have 

 mentioned such practical applications of those 

 principles to agriculiure and ihe various concerns 

 of rural economy, as frequent trial has placed be- 

 yond (piestion. Whilst preparing this essay for 

 the public, many other praciical applications have 

 suggested themselves to my mind, but I have pur- 

 posely passed them h}^, lest some error, which a 

 better knowledge of practical agriculture than that 

 which I possess would at once detect, should bring 

 ihe whole into discredit. In attempting to apply 

 a scientific principle to any practical purpose, there 

 are always many circumstances to be taken into 

 account; and if the person attempting so to apply 

 it fails properly to consider each and every one of 

 these, he will necessarily subject himself to entire 

 failure in the result. Many of these circumstances 

 may be such as are known only to practical men ; 

 more especially is this likely to be the fact with re- 

 spect to a science, which like that of agriculture, 

 js yet in its infancy. If the attempt to apply the 

 principle should result in failure, many persons, 

 not discerning the true source of that failure, will 

 call the principle in question, or perhaps will look 

 upon it as conclusive proof of the uselessnees of 

 science, and confirm themselves in the belief of 

 the common sentiment " a grain of experience is 

 worth a ton of theory," understanding by the term 

 theory, scientific knowledge in general. If I mis- 

 take not, a great deal of that invidious distinction 

 which is sometimes made between scientific and 

 practical men arises from this very source. 



In order that we may see more clearly the true 

 cause of such failures, and may learn what is the 

 inference which may properly be drawn fi-om tliem, 

 I will mention an example. Sir H. Davy some 

 years since, discovered that a sheet of copper 

 when exposed to sea water, might be effectually 

 protected from corrosion, by soldering to it a small 

 piece of zinc. This was a necessary result flom 

 the nature o!" galvanic action. At once he con- 

 cluded, and the conclusion seemed a very natural 

 one, that this discovery would admit of a most 

 valuable practical application, in the preservation 

 of the copper sheathing of ships. A trial was 

 made; the sheathing of a ship fitting out for a 

 long voyage was prepared under his direction. 

 V0L.2VII-8I 



When this ship returned liom the voyage, and 

 her bottom was examined, it was Ibund that her 

 sheathing was indeed sale, but that it was covered 

 in many places to the depth of more than a foot, 

 with sea-weed and marine molkiscfp, and that 

 these, by rendering her bottom rough and ragged, 

 had retarded her sailing so much, that more mo- 

 ney was lost in time and the wages of her crew, 

 than was gained in her protected sheathing. 

 Whilst her coppered bottom was exposed to the 

 (iee action of sea water, it was continually covered 

 with a poisonous coating consisting of the corroded 

 metal, which prevented sea-weed and moiluscce 

 from fastening themselves to it ; but so soon as 

 this poisonous matter was prevented Irom forming, 

 they fastened themselves to the copper with as 

 much, and even greater freedom, than they would 

 have done to a rock or log of wood in similar cir- 

 cumstances. In this instance the failure resulted 

 entirely ii'om not taking this last circumstance into 

 account. Perhap.s, had Davy consulted some prac- 

 tical seamen, they might have suggested this dif- 

 ficulty. The principle in accordance with which 

 he acted, was a correct one, and his fliilure in no 

 way affected the evidence of its truth ; and' fur- 

 ther, this principle may yet be applied to the very 

 purpose to which he attempted ;o apply it ; if some 

 cheap poisonous substance can be found which may 

 take the place of the poison atiorded by the corro- 

 sion of the metal, or if b}^ any other means, ma- 

 rine molluscsB can be prevented Irom fastening 

 themselves to the sheathing of ships, and the very 

 failure of Davy may be directly instrumental in 

 leading to some discovery which will accomplish 

 the thing sought; and yet doubtless this failure 

 has been set down by many to the discredit of 

 science. 



Lest i should fall into such errors as this, and 

 thus bring discredit upon a study which I believe 

 would contribute more to the advancement of ag- 

 riculture, (if practical agriculturists would acquaint 

 themselves with it, and make a proper use of their 

 knowledge,) than almost any other which could be 

 mentioned, I have contented myself unlh giving a 

 simple statement of the principles of vegetable 

 physiology, and purposely avoided attemfifing to 

 apply them to practical agriculture, excepting in 

 those cases where trial has been aheady made, 

 and the results have proved satisfi^ctory. In such 

 circumstances, F hope I shall not he thourrht to be 

 needlessly transgressing the proper limits of my 

 subject, in devoting the present rhaptpr to some 

 genera! remarks upon the application of scientific 

 knowledge to practical purposes, and Ihe proper 

 character of experiments. 



Experimenting has been significantly termed 

 by Lord Bacon, "asking questions of nature." 

 Nature, in all circumstances, is subject to certain 

 fixed and invariable laws. Our world is not a 

 mere chance production which has happened to be 

 what it now is ; but in every part is contrived with, 

 the greatest wisdom and put together with con- 

 summate skill. The only proper object of experi- 

 mental research is to ascertain these laws, in orde 

 that, acting in accordance with them, we m- 



