fitting out

the forfeiture is incurred, either by fitting out, or, in other words, preparing a vessel, within the United States; or, by causing a vessel to sail from the United States for the purpose of carrying on the slave trade... it is the preparation of the vessel, and the purpose for which she is to be employed, that constitute the offence, and draws after it the penalty of forfeiture. As soon, therefore, as the preparations have progressed, so far as clearly and satisfactorily to show the purpose for which they are made, the right of seizure attaches.