E/MJ : engineering and mining journal . ut the Philippini ucture in which salt wa-in w! 1020 ENGINEERING AND MINING JOURNAL Vol. 102, No. 24 are several such buildings in good condition. However,the concrete in them is unusually dense, and it is thoughtthat their success in withstanding the influence of thesalt is due to the density of the concrete. Engineers in the Philippines have been accordingly ad-vised that all use of salt water in concrete structures isdangerous and that the use of beach sand and beach gravelshould be permitted only after thorough washing withfresh water. Simple Sl&aft
E/MJ : engineering and mining journal . ut the Philippini ucture in which salt wa-in w! 1020 ENGINEERING AND MINING JOURNAL Vol. 102, No. 24 are several such buildings in good condition. However,the concrete in them is unusually dense, and it is thoughtthat their success in withstanding the influence of thesalt is due to the density of the concrete. Engineers in the Philippines have been accordingly ad-vised that all use of salt water in concrete structures isdangerous and that the use of beach sand and beach gravelshould be permitted only after thorough washing withfresh water. Simple Sl&aft Gate at JuaimctiioiniMniaei, Warren, Airig,, At the Junction shaft of the Calumet & Arizona Min-ing Co., Warren, Ariz., a shaft gate is used that is simpleand cheap and has an inherent tendency to stay shutwhen it should be shut and to stay open when it shouldbe open. The gate consists of a piece of IV2- or 2-in. pipe onone end of which is a semi-circular section of cast ironpivoted as shown. When the gate is closed, the weight. A SIMPLE SHAFT GATE f the pipe has a greater moment-arm than the counter-weight and it naturally stays closed. When the gate islifted about two-thirds of the way up, the center ofgravity changes so that the counterweight tends to keepon rotating and after the pipe passes the vertical themoment of both pipe ami counterweight act together tohold the pipe against the stop A. A plate B is used onthe center post to give a bearing, and the iron straps Csupport the bearing pin and provide a guide for thecounterweight so that the far end of the gate never missesthe clip D and falls down. It is a clever gate. How T© WatesrpiroofF TTJirawfiimgs A few methods for waterproofing drawings were notedby F. W. Salmon, in Engineering News, Nov. 30, 191G,all of which are useful and satisfactory. A. Give the drawing several light coats of white shellacdissolved in a grain alcohol, letting each coat dry beforethe next is applied. Orange shellac and even wood alcoholmay be
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Keywords: ., bo, bookcentury1900, bookdecade1910, booksubjectmineralindustries
