20 REPORT—1845. 
IV. From Professor Loomis of New York University to Lieut.-Col. Sabine. 
New York University, Feb. 28, 1845. 
Dear Si1r,—Having been invited to express my opinion respecting the im- 
portance of continuing the establishments so liberally set on foot by the 
British government for magnetic and meteorological observations, while I 
admire the liberal policy of the government in what has already been done, 
I do not hesitate to express it as my conviction, that the immediate abandon- 
ment of these establishments would prove highly prejudicial to the cause of 
science. The present combined movement for magnetic observations had for 
its object the discovery of the cause of all terrestrial magnetic phenomena, 
This was to be accomplished by simultaneous observations of each of the 
magnetic elements at numerous stations scattered over the globe. The 
observations however must not only be made, they must all be brought to- 
gether, compared, discussed, interrogated, before we can know what lan- 
guage they speak ; they must be published and placed in the hands of all who 
are interested in the subject. The observations themselves constitute but the 
raw material; they are of little value until they are reduced, and it is dis- 
covered what general truths can be derived from them. 
But it may be asked, whether, having made our observations, we may not 
now safely pause until we have ascertained what results they are to furnish ? 
To this there are numerous objections; one of which is, that to suspend tem- 
porarily the present system of observations, would in many cases lead to their 
entire abandonment. But have not observations already been made sufficient 
to secure the object originally proposed? I presume no one is ready to 
answer this question in the affirmative. It commonly happens in experimental 
research, that after a series of fortunate experiments which have shed light 
on what was before shrouded in mystery, a careful comparison of all the ex- 
periments suggests some new combination, which, like an expertmentum crucis, 
would enable us finally to decide between conflicting theories. It is not 
reasonable to anticipate any better success in our magnetic researches. A 
discussion of the past observations will suggest plausible explanations which 
are consistent perhaps with all the observed phenomena; but to preclude all 
objections, it may be necessary to observe the phenomena under varied cir- 
cumstances; perhaps at new stations peculiarly situated, perhaps with pecu- 
liar instruments. To abandon the present system, therefore, before a thorough 
discussion has been undertaken of the observations already made, may be to 
stop short in the race when the prize is just within our reach. Let the obser- 
vations be published as rapidly as possible, let them be freely circulated. 
When the object for which the observatories were founded has been shown to 
be attained, then let them be dismantled. But suppose they are abandoned 
forthwith, and after a comparison of all the observations, we arrive at the pro- 
bable clue to all the phenomena of terrestrial magnetism ; but still some doubt 
remains, which however might probably be cleared up by a further continu- 
ance of the observations, with perhaps some slight modifications suggested by 
experience. Should we not condemn that ill-judged ceconomy, which, after 
forming a liberal plan for the accomplishment of a glorious end, stopped short 
in its execution before ascertaining whether or not the object in view had been 
attained? Surely it is the dictate of wisdom to hold on to the present posi- 
tions until we have ascertained whether the enemy has really surrendered ; 
and if he still holds out, let us inquire whether a different system of tactics 
would not promise better success. Let us not then abandon our present posts 
until we ascertain that our objects are accomplished, or until it is clear that 
success is not to be expected. 
