From the New York Advertiser.

It will be recollected, that a society was formed in this city, sometime since, under the title of 'the Indian Board, for the emigration, Preservation and improvement of the Aborigines of America.' Subsequent to its formation, Col. Thomas L. McKenney, of the city of Washington, was here, and by invitation, made an address to the members, on the subject. Since that time, we have seen a letter from Col.McKenney to a gentleman in Boston, on the general subject of removing the Indians, from which the following passage is extracted.

'I notice much writing, and labored essays to prove, from treaties, and otherwise, the rights of the Indians, and arguments strenuously enforced showing that our relations to these people, as to their particular locations ought not to be violated. So far as these writing imply any intention in the Executive to drive the Indians off, by force; or even refuse (within legal and constitutional limits) to protect them, they are wholly without application. This, I humbly conceive is not the question. It is one of another sort-and embraces the simple proposition, what is best to be done, all things considered, for saving and bettering the condition of the Indians? As well might labored essays be written to prove the right of a family of children to a gamily mansion, which had been secured to them by inheritance, and by every other sort of binding title, and such right brought to bear upon the guardian of these children, as applicable, and conclusive against his efforts to persuade such of these children as might survive the action upon their lives of some deadly elements, originating in the very mansion itself, to leave it and go where they would be free, in all the future, from their desolating effects. If the inheritors of this mansion were not idiots, as well as children, they would go-especially when it should be demonstrated to their very senses that nothing awaited them in the mansion, but extinction; and everything preserving and beneficial awaited them on their removal from it. For my own part, I look upon the Indians-(with some few exceptions of course)- to be nothing but children, and am convinced that nothing would be so good for them as to treat them as such-provided the object of the treatment was to improve their condition; and those who undertook their guardianship were qualified, both as it regards the power and the will to advance their happiness. Nobody questions the kind designs of the government of this country towards these people; and it were time thrown away to prove that it has when the Indians are upon lands belonging to the Federal Government, the power.'

We presume Col. McKenney, in writing this part of his letter, had immediate reference to the very able and unanswerable essays that were originally published in the National Intelligencer at Washington, and have since been so extensively republished throughout a large portion of the United States, under the signature of 'William Penn.': The author of these essays deserves the thanks of all the friends of right, truth, and justice-of the character of the government and the reputation of this country. He has espoused the cause of the Indians with so much industry, zeal, force, and ability, that the supporters of the sentiments and policy of those who would improve their condition by removing them from their property, possessions, and homes into the wilderness, must resort to the question of expediency, to vindicate a single step in the prosecution of their object.

Col. McKenney says,'that so far as the writings in the newspapers imply any intention in the Executive to drive the Indians off by force, or even refuse (within the legal or constitutional limits) to protect them, they are wholly without foundation.' But with all due deference to the superior understanding and intelligence of this gentleman on the subject, we would remind him, that there are many ways of accomplishing such an object as the Executive, and Col.McKenney, and the New York 'Indian Board,' and other 'friends' of the Aborigines have in view, viz. 'clearing them out' from Georgia and Alabama and sending them to the woods, besides driving them at the point of the bayonet. A treaty like multitudes of others that have been made with different tribes under circumstances equally coercive as of actual force had been used, would answer the purpose. It is an easy thing to bring Indians to terms, when they know before hand that they must in the end come to terms. They have discernment enough to see through our plans and policy, though they have not strength enough to resist them. 'Nobody,' says Col. McKenney, 'questions the kind designs of the government towards these people.' We are sorry to be under the necessity of contradicting this gentleman, but we must say that we believe multitudes of people question the fact and we know of a good many that entertain a directly opposite opinion. When we hear it openly said, and repeated, in public newspapers, and elsewhere, by those who would at least lay claim to respectability of character, that Indian titles to lands which they have possessed for unknown ages, are of no value;- that treaties solemnly entered into with them by our national government are not constitutional, and of course not obligatory even upon us; and when we see the administration of the national government putting forth extravagant, and preposterous sentiments on the general subject of Indian rights, and Indian security; all the professions of friendship they may severally make of kindness and friendship to these feeble and defenseless objects of personal speculation, and political hostility, will receive but little attention, or gain but little credit with men of experience and discernment.

That the object is to get rid of them, that others may seize and divide their property, we do not entertain a doubt.