2. It is not to be expected that material will be sought the transportation of which, even with the best precautions, involves a necessary injury,--as for instance, by strain,--or a contingent injury in its use outside of the walls of the institution owning it by persons over whose use it has no supervision. A stipulation for its use within the walls of the borrowing library, while entirely reasonable, may not cover the case completely, as the responsibility for the care of the material cannot, by a mere stipulation for care, be transferred from the owning to the borrowing library. 3. Subject to 2, the important service in inter-library loans being to make generally available the unusual book for the unusual need of the serious investigator, the fact that the book needed is either rare, or part of a set which may be marred by the loss of a single volume, or that it is even unique, as for instance a manuscript, ought not to be conclusive against the loan, for it is just through such material that the inter-library loans may render their most important service. 4. The applicant library should refrain from applying (a) for ordinary books which are within its constitutional duty to supply to its immediate readers, or (b) for unusual books requested for a purpose which it knows to be trivial, or by a person of whose discretion and seriousness it is not assured, or (c) for books which, within the legitimate provisions of a loan are to be had from some institution nearer at hand, or having a nearer constitutional duty to it and to the constituency which it serves, or (d) for books which upon their face must be in constant use in any library possessing them.