GENTLEMEN.—I propose, in the prosecution of my duties as Director of Machinery in the Crystal Palace, to test the qualities of different oils offered by manufacturers for lubricating machinery. To this end I propose to re-receive, say five gallons, from each manufacturer or seller of such oils or lubricators, who is willing to submit the same to trial under the lollowing rules :— A suitable person shall receive such oils or lubricators, and deposit them in cans containing 2 gallons each—the one a duplicate of the other, and both bearing the same number —making five gallons of one kind from one manufacturer. If one person sends more than one kind, it must be understood that there shall be two cans of 2 gallons of each sample. The person in charge of the oils will record the numbers of the cans, and the names of the depositors. I will see that the same numbers as those on the cans, are marked on the hangers of 800 feet of shafting, and that the same boxes will be oiled with the tarne oil for :o:ir month?, Employing no more than what is suitable lot tile (tarfoct. lubrication ol each joint. At the eodEMftU't m'ojitha, the oils left in iifFermtggsKiL b measured, and the bearings aBHP"* ''Xi*f ' see their state, ahiJBfiBpS'uiy of ttiirwaste oil in the dripping eSpPl will be assisted by competent persofitfeither as judges in the Exhibition, or selected on account of skill and experience in such matters, and will report all the facts connected with this testing of lubricators. On the closing, when the report is made, the record kept by the person who received the oils and kept the names ot the contributors secret, shall make known the same, so that the public can judge of the merits of different, lubricating materials employed ior machinery according to the price at which they are sold. The greatest care will be exercised to have the test a most perfect one. JOSEPH E. HOLMES. New V/ork, May 7bh, 1853. I 1 itUSts w UU sen iuui.Uu..t) who are not afraid of testing them with others, will have a good opportunity of so doing.— [ED.