LOCAL VARIATIONS AND VIBRATIONS OF EARTH’S SURFACE. 59 
been designed not to give correct results, but the greatest uncer- 
tainty in working. Certainly ours justified such a view, and was 
most unsatisfactory in every way. owever, in the results of 
azimuth, Mr. Smalley thought he could trace the annual curve 
which had been found in the Greenwich and two or three other 
Observatory on a large hill of sandstone rock of which the north 
and west sides are cut down about 40 feet, exposing bare rock 
faces to the sun and weather. And it is interesting, now that we 
sandstone 8 feet 6 inches long, 3 feet wide, 18 inches thick, which 
rests on a mass of masonry 16 feet long, 5 feet wide, and has for 
foundation the solid sandstone of which the hill is composed. 
You will see that although the hill is not the place an astronomer 
would choose to put an observatory, it is yet far more stable than 
it was supposed to be, in fact it is quite evident that the faults of 
the old instrument were unjustly laid on the hill. If we could only 
stop the production of smoke, which seems to me to be increasing 
ina geometrical ins the site would do for many years to come. 
wing the annual variations of the level and 
azimuth of the new roel ardneat will show you that the level 
goes through a regular annual variation, the eastern pier rising in 
June to its highest point the same as it ‘does at Greenwich, and at 
least some other European Observatories. The range in our level 
is a small one, only about 10”, and so regular that the level errors 
increase of level, probably due to the settling of the pier, which 
had been in part rebuilt for the new instrument, and a subsequent 
fall, as will be seen in the following table. 
Level errors of the Sydney Transit Instrument :— 
Highest reading. Lowest. Mean, 
SOT vives, are vee PU’ slice Lda! eee 5 
TORS a ereceres ce ROU vrecss ae deli 10:3 
ROTO Asoecestess IDS © cues TO = tee 13-0 
POOR. cue vegies AGO Saree OO An 5 
FOOL oo vaasisers i! aaa re 100 cs 15-0 
BORE tcriy cs pete ISO ca gs ee en 
BOOS ii cesctvess TOU ace oO i 135 
BOOE oocsce vues 190 ie (Signe 
