The concrete elevator, which is also combined with the scaffold, consists of a series of buckets carried upon two parallel endless chains passing over two pairs of wheels.  On the under frame is fixed a hopper, into which is thrown, either by hand or from a concrete mixer running upon the rails, the material to be hoisted, and from which it gravitates into a narrow channel, through which pass the buckets (attached to the chain) with a shovel-like action.  The buckets, a motor being applied to one pair of wheels, thus automatically fill themselves, and on arriving at top are made to tip their contents, and jar themselves, automatically into a hopper by means of a small pinion, keyed to the shaft by which they are attached to the endless chain, becoming engaged in a small rack fixed for that purpose.  From the upper hopper the material is taken away to the required destination by means of a worm working in a tube.  For varying heights, extra lengths of chain and buckets are inserted and secured by a bolt passed through each end link, and secured by a nut.  By using this scaffold, a saving in plant, cartage, and labor is effected.  The elevator may also be used for raising any other material besides concrete.

Such is the new system of concrete construction and scaffolding of Messrs. West, which appears to be based on sound and reasonable principles, and to have been thoughtfully and carefully worked out, and which moreover gives promise of success in the future.  We may add in conclusion that specimens of the work and a model of a scaffold are shown by Messrs. West at their stand in the Inventions Exhibition.—­Iron.

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[Illustration:  Albany buildings Southport.  E.W.  Johnson, architect.]

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THE BLUE PRINT PROCESS.

R.W.  Jones.

1.  Cover a flat board, the size of the drawing to be copied, with two or three thicknesses of common blanket or its equivalent.

2.  Upon this place the prepared paper, sensitive side uppermost.

3.  Press the tracing firmly and smoothly upon this paper, by means of a plate of clear glass, laid over both and clamped to the board.

4.  Expose the whole—­in a clear sunlight—­from 4 to 6 minutes.  In a winter’s sun, from 6 to 10 minutes.  In a clear sky, from 20 to 30 minutes.

5.  Remove the prepared paper and pour clear water on it for one or two minutes, saturating it thoroughly, and hang up to dry.

The sensitive paper may be readily prepared, the only requisite quality in the paper itself being its ability to stand washing.

Cover the surface evenly with the following solution, using such a brush as is generally employed for the letter-press:  1 part soluble citrate of iron (or citrate of iron and ammonia), 1 part red prussiate of potash, and dissolve in 10 parts of water.