Jury 30, 1914] 
NATURE 
571 
the Zufi and the Hopi, according to their legends, 
with whom they still live. 
Although Dr. Fewkes refers to the Hohokam as 
being ‘‘ homogeneous,”’ the fact that they practised two 
forms of burial would lead one to suppose a mixture 
of two cultures. He also points out that whereas the 
Hohokam dwellings were rectangular, those of the 
Pima are circular in form, but some of the Pima 
houses are rectangular; also the Pima do not burn 
their dead. Dr. Fewkes concludes by saying: ‘In 
considering the prehistoric migrations of agricultural 
peoples in the south-west, especially with respect to 
changes in culture and to diminution of population, 
we must not lose sight of the influence of increased 
salinity due, directly or indirectly, to long-continued 
prehistoric irrigation. This cause was perhaps more 
effectual than human enemies or increased aridity [as 
Ellsworth Huntingdon claims] in breaking up the pre- 
historic culture. If barrenness of the soil, due to the 
This new base was measured near the town of 
Lossiemouth, on the southern shore of Moray Firth, 
and the operations have been described in Professional 
Paper, No. 1, 1912, where the probable error of the 
final value is given as 1 in goo,ooo. The original 
triangulation was computed in terms of the, 1o-ft. 
standard bar of the Ordnance Survey, and a useful 
chapter of this paper places on record the relations 
between this bar, the French legal metre, and the 
international metre of the Bureau International des 
Poids et Mesures. The three stations—Corriehabbie, 
Mormon Hill, and Knock of Grange—in the principal 
triangulation were selected near the Lossiemouth 
base for the work of verification; but some difficulty 
was experienced on account of the observation points 
not having been marked originally in as permanent 
a manner as is now employed, wooden pickets having 
been used. All triangulation points that are now 
being occupied and those of the test triangulation are 
Bird's-eye view of Compound A, from the east. 
cause mentioned, led to the abandonment of populous 
aboriginal compounds, this fact has an important bear- 
ing on the future of the white farmers in the Gila and 
Salt River valleys.” A. C. Happon. 
THEAORRINCIPAL TRIANGULATION. OF 
THE UNITED KINGDOM.! 
ites publication of the Ordnance Survey deals 
with a subject of especial interest, since it sets 
forth the operations which were undertaken in 1910, 
Ig11, and 1912, in order to test the accuracy of a 
portion of the principal triangulation of the United 
Kingdom, and discusses the results obtained. This 
triangulation, which was observed during the seventy- 
two years, 1783-1855, comprises 552 triangles, and the 
mean error of an angle as given by Ferrero’s formula, 
2 
m=4/*4 is +1-8”, a value which is somewhat larger 
than that of recent first order triangulation. This 
raised the question whether the triangulation was suit- 
able for incorporation with recent Continental geodetic 
work. It was therefore decided to measure a new 
base in a part remote from the principal bases of the 
triangulation at Lough Foyle and on Salisbury Plain, 
and to re-observe a portion of the principal triangula- 
tion in its neighbourhood. 
1 Ordnance Survey. Professional Papers, new series, 2. ‘‘ An Investiga- 
tion into the Accuracy of the Principal Triangulation of the United 
Kingdom.” By Capt. H. St. J. L. Winterbotham. With an Introduction 
by Col. C. F. Close. Pp. 20+v plates. (London: H M. Stationery Office ; 
Wyman and Sons, Ltd., 1913.) Price 2s. 
NO. 2335, VOL. 93| 
marked with bronze bolts set in rock or in a thick 
foundation of concrete. 
The angles were measured with a 12-in. theodolite 
constructed for this work by Messrs. Watts and Sons, 
the horizontal circle being read by means of three 
microscopes. Eight arcs were observed, and the mean 
error of an angle in the twenty-nine triangles is given 
as +0:517". 
For marking the points to be observed both lamps 
and heliostats were provided, the pattern being the 
same as that used in the measurement of the arc of 
meridian in Uganda; but it was rarely possible to use 
the heliostats even during the exceptionally fine 
summer of 1911, and practically all the observations 
were made on lamps. ‘The theodolite is briefly but not 
exhaustively described, and a detailed investigation of 
it would be of much interest. The readings of the 
horizontal circle are to single seconds, and to tenths 
of a second by estimation; the vertical circle is only 
6 in. in diameter, and is read to one minute of arc, 
being merely intended for setting to any known angle 
of elevation. 
A special plumbing telescope, which is screwed into 
the upper horizontal plate, and can be focussed to view 
marks at from 3-20 ft. distant, provides the means 
for accurately centring the instrument over the station 
mark. Concrete observing pillars were used at each 
station, and were made with a central vertical shaft 
over the station mark, this being illuminated through 
horizontal view-holes provided in the base of the pillar. 
A large triangulation error which was found in the 
