irteen
types of fertilizers in common use at the time. Gift of Dr. John B.
Blake, Washington, D. C.

230. Cast-Iron Centrifuge, 1960. USNM 238503; 1961. A centrifuge used
for running the Babcock milk test, which determined the percentage of
butterfat. Gift of Dr. John B. Blake, Washington, D. C.

231. Insecticide, 1960. USNM 238503; 1961. A sample of a Pyrox
insecticide in common use in 1960. Gift of Dr. John B. Blake,
Washington, D. C.

232. Hoe, 20th century. USNM 239136; 1961. A socket-type, three-tine hoe
used to weed vegetable gardens, tobacco, and similar row crops. Gift of
Mrs. Henry H. Byrne, Washington, D. C.

233. One-Row Planter, about 1870. USNM 237951; 1961. The gears from the
drive-wheel mesh with a set of gears that turn the seed plate. The
distance for dropping the seed could be determined by the size of the
gear used on the drive-wheel. Gift of H. C. Cole, Crestline, Ohio.

234. Portable Gasoline Engine, 1903. USNM 240546; 1961. This machine
provided belting power for operating feed mills, cream separators, wood
saws, etc. It generated 2 hp at 300-600 rpm. It was covered by two
patents dated April 7, 1903. Gift of New Holland Machine Co., New
Holland, Pennsylvania.

235. Cotton Planter, 20th century. USNM 240545; 1961. This one-row,
horse-drawn cotton planter drilled cottonseed in rows by means of a
revolving wooden drum with one-inch holes spaced around the center of
the drum. Gift of Lester Souter, Boerne, Texas.

236. Wooden Spade, about 1840. USNM 240543; 1961. This wooden spade has
a metal cutting edge. Purchased from Mrs. H. J. Cummings, Washington, D.
C.

237. Model of McCormick Reaper, 1831. USNM 236710; 1961. A full-scale
model of the 1831 McCormick reaper. Gift of Franklin Institute,
Philadelphia, Pennsylvania.

238. Hoe, date unknown. USNM 239502; 1961. This is a socket-type hoe
with a half-moon cutting blade. Gift of Dr. Ivor Cornman, Miami,
Florida.

239. Curd Breaker, mid 19th century. USNM 239502; 1961. This tool for
cutting cheese curds has four 15-inch parallel blades. Gift of Dr. Ivor
Cornman, Miami, Florida.

240. Wooden Brace, possibly mid 19th century. USNM 239502; 1961. This
implement was used to hold open the split carcasses of hogs. Gift of Dr.
Ivor Cornman, Miami, Florida.

[Illustration: Figure 20.--A view in the Hall of Farm Machinery,
National Museum of History and Technology. The Holt combine in 1887
(Catalog No. 241) is at left. The Victor mowing machine of