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IMPORTANT FACTS ABOUT STUCCO
only dainty fare, a craftsmanlike table and
beautiful linen, but dishes which would add
the completing touch to the sought-for har-
mony. Pieces made with such an end in
view cannot be hurried; but that is no
drawback, for possession which is too easy
leads to a certain carelessness of attitude
toward the article so obtained and thence to
the curse of wastefulness because it is "so
easy to get another."
   We started our little industry in the cellar
 of a private dwelling, and today our plant
 occupies the first floor and basement of a
 house under the shadow of the old North
 Church where Paul Revere's signal lanterns
 were hung, and opposite the green turf and
 ancient elms which shade the resting places
 of some of Boston's first citizens in Copps
 Hill Burying Ground.
   Our pottery includes the usual necessities
-clay bins, sifting, grinding and clay-
pressing machinery, wheels, drying closets,
racks innumerable, a whirler for mold
work, tables for painters, a color mill for
grinding glazes, benches for dipping ware
and-most important of all-a good kiln.
The utensils include vessels for glazes,
modeling   tools and painting  materials,
while the items which appear oftenest on
the expense account are packing materials,
clay, cones, fire brick, fuel, chemicals, "re-
pairs on kiln and machinery," plaster for
molds, and stilts. But equally important
though less tangible factors in the work are
the personal interest and craftsmanship that
go into the making of Paul Revere pottery.
IMPORTANT FACTS ABOUT
STUCCO: RALPH              L. SHAIN-
WALD, JR., A.M.
HE ease with which stucco lends it-
         self to artistic treatment, has
         tended toward a precocious devel-
         opment that has been harmful.
The trouble is that a stucco job which at
first appears to be an artistic gem, gradual-
ly develops flaws which may finally over-
shadow the original beauty.
  What is the cause of the "checking" and
"hair-cracking?" Is it superficial, or is it
hidden in the physiochemical composition
of cement? Much valuable study has been
devoted to the external treatment of stucco,
but few have stopped to question its inter-
nal composition. Let us therefore study
some inside facts of stucco mortar.
  The subject is an interesting one and the
conclusions startling. Who would have
thought, for instance, that cement acts like
wood: swelling up on wetting and contract-
ing on drying? But this is proven by care-
ful measurements.
   A. T. Goldbeck, of the U. S. Department
 of Agriculture, showed this in experiments
 described in the Engineering Record of July
 8, 1911 (page 45). His researches were
 confirmed by Prof. A. H. White, working
 independently in the University of Michi-
 gan and published in the Engineering Rec-
 ord for July I5, 1911 (page 73). Both of
 these gentlemen proved scientifically and
 conclusively that mortar and concrete ex-
 pand on wetting and contract on drying, the
 action keeping up for years.
   In some cases the amount of expansion
 (due to wetting) was as great as that due
 to IOO degrees increase of temperature.
 This is a startling fact, when it is remem-
 bered that concrete expands with heat just
 as much as iron does. The strains due to
 wetting and drying are therefore very se-
 vere and come quickly and repeatedly. It
 is not difficult to see why this should be
 such a serious source of cracking.
   It is fortunate that only the cement is
affected, the sand remaining practically un-
influenced by moisture. Therefore lean
mortars are much less affected than rich
ones: a i :3 stucco when moistened expands
much less than a I :2. But as Professor
White says, "If a stucco is lean enough to
avoid cracks water will go through it free-
ly, and if it is rich enough to keep out wa-
ter it will crack."
   In Italy, where stuccos have been used
 for centuries, masonry walls were thick and
 waterproof in themselves. Cement was
 made from pulverized natural rock, and
 lean stucco mixtures were a matter of
 economy. The passage of ages has devel-
 oped comparatively little checking in the
 Italian stuccos. But today, in America,
 Portland cement is cheap, walls are thin
 and climate severe, so that rich mixtures
 have been used in the attempt to get cheap
 waterproofing. The result is excessive hair-
 cracking.
 It is, of course, true that a T :2 stucco is
 more waterproof than a I :3, but it is very
 much more liable to crack. On the other
 hand, a I :3 stucco properly applied is safe
 from cracking, though very porous. This,
 then, is the dilemma which confronts the
constructor: how   to make stucco lean
enough to avoid cracks, yet non-porous
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