. Cement and concrete. could representfive pounds each, instead of two pounds, the value of the grad-uations now on the single lever machines. 203. FORMS OF CLIP. — Since cement has been tested bytensile strain, it has ever been a problem to obtain a clip whichwould give a perfectly true axial pull on the briquet. Variousforms of clips have been used from time to time, but none ofthem has proved satisfactory in all respects. To trace the his-tory of the development of the clip is not warranted by itsinterest, but it may be said that in some of the early forms the BREAKING THE BRIQUETS 139 head
. Cement and concrete. could representfive pounds each, instead of two pounds, the value of the grad-uations now on the single lever machines. 203. FORMS OF CLIP. — Since cement has been tested bytensile strain, it has ever been a problem to obtain a clip whichwould give a perfectly true axial pull on the briquet. Variousforms of clips have been used from time to time, but none ofthem has proved satisfactory in all respects. To trace the his-tory of the development of the clip is not warranted by itsinterest, but it may be said that in some of the early forms the BREAKING THE BRIQUETS 139 head of the briquet was held between two plates and clampedtight enough to develop sufficient friction to transmit the later forms of briquets are made with a shoulder or withwedge-shaped ends to allow the clip to grasp them. Mr. JohnGrant, Mr. Alfred Noble, General Gilmore, Mr. J. Sonderickerand Mr. D. J. Whittemore have each designed or adapted dif-ferent forms, and more recently Mr. S. Bent Russell and liuniiiiiE 3 I aA Vt Yk 0 I Z Zin. Fig. 6. — RIEHLE ENGINEERS* STANDARD CLIP W. R. Cock have each devised a clip which will be mentionedbelow. 204. Form in Most General Use. — The clip in most generaluse in the United States is of the general style shown in Fig. differs only in detail from the form recommended by theAmer. Soc. C. E. Committee of 1885, which has been called 140 CEMENT AND CONCRETE the Engineers Standard. The general form is pear shaped;the briquet is grasped at the points of reverse curve at the sideof the briquet, giving an area between opposite gripping pointsof about one and a quarter square inches. The gripping pointsare rather too sharp, when new, as they have a tendency tocrush the briquet locally. The width of the bearing increaseswith the amount of wear the clip sustains. The clip is providedwith a conical pivot, which rests in a cone-shaped cavity at-tached to the machine, so that the two parts of the clip arefree to swing. In a
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