annular bit, accompanied by a quantity of chilled steel shot; for soft
rock, a toothed bit is used.

Diamond drill holes are rarely straight, and usually deviate
considerably from the direction in which they are started. Very deep
holes have been found to vary as much as 45 deg. and even 60 deg. from
their true direction. This is due to the fact that the rods do not fit
closely in the hole and therefore bend. It is also likely to occur in
drilling through inclined strata, specially when of different degrees
of hardness. By using a long and closely fitting core-barrel the
liability to deviation is reduced, but cannot be wholly prevented.
Holes which are nearly horizontal always deflect upward, because the
sag of the rods tilts up the bit. Diamond drill holes should therefore
always be surveyed. This is done by lowering into the hole instruments
for observing at a number of successive points the direction and
degree of deviation.[1] If accurately surveyed a crooked hole may be
quite as useful as a straight one.

AUTHORITIES.--For further information on boring see _Trans. Amer.
Inst. Mining Engs._ vol. ii. p. 241, vol. xxvii. p. 123; C. le Neve
Foster, _Text-book of Ore and Stone Mining_, chap. iii.; _Gluckauf_,
9th December 1899, 20th and 27th May 1905; _Scientific American_, 21st
August 1886; _Engineering and Mining Jour._ vol. lviii. p. 268, vol.
lxx. p. 699, vol. lxxx. p. 920; _Trans. Inst. Mining Engs._, England,
vol. xxiii. p. 685; _School of Mines Quarterly_, N. Y., vol. xvi. p.
1; _Zeitschr. fur Berg- Hutten- und Salinenwesen_, vol. xxv. p. 29;
Denny, "Diamond Drilling," _Mines and Minerals_, vol. xx., August
1899, p. 7, to January 1900, p. 241; _Mining Jour._, 26th January
1901; _Mining and Scientific Press_, 28th November 1903, p. 353; _Ost.
Zeitschr. fur Berg- und Huttenwesen_, 21st May, 4th June 1904; _Trans.
Inst. Mining and Metallurgy_, vol. xii. p. 301; _Engineering
Magazine_, March 1896, p. 1075. (R. P.*)

FOOTNOTE:

[1] Brough, _Mine Surveying_, pp. 276-278; Marriott, _Trans. Inst.
Mining and Metallurgy_, vol. xiv. p. 255.

BORIS FEDOROVICH GODUNOV, tsar of Muscovy (c. 1551-1605), the most
famous member of an ancient, now extinct, Russian family of Tatar
origin, which migrated from the Horde to Muscovy in the 14th century.
Boris' career of service began at the court of Ivan the Terrible. He is
mentioned in 1570 as taking pa