95 
effort and energy implied. Such are the astronomical re- 
sults of this most honorable and useful expedition ; yet these 
constitute by no means all the information it collected. 
The observations on earthquakes are most valuable and 
extensive, comprising not merely those made under Gilliss’s 
immediate direction, but others also, instigated or collected 
by him, of the same phenomena at other places than Santi- 
ago, during his stay in Chile. Among these is an admirable 
series, not less complete than his own, observed by Sefior 
Troncoso at La Serena, the capital of the province of Co- 
quimbo, about 250 miles to the north of Santiago. These, 
and a collection of the accounts of the chief Chilian earth- 
quakes on record, are included in his first volume, and war- 
ranted in Gilliss’s opinion sundry important deductions, the 
chief of which, apart from those of a purely local nature, 
are:— That there are no permanent centers of disturbance, 
the apparent direction of the vibrations varying at each 
Occurrence. That a large proportion of the tremors are 
neither undulations nor vibrations, but rather rapid ver- 
tical displacements of the crust of the earth, almost, if 
not absolutely simultaneous over the disturbed district. 
_ And finally, the very curious one, that the season of the ~ 
_ year seems to exert some influence, —the average monthly 
shocks at Santiago during thirty-five consecutive months 
being 132 for April, while it reached in no other month so 
large a number as 144, and similarly at La Serena, the aver- 
age number during twenty-eight months being fifteen for 
November, eight for December, and for the mean of the 
other months less than four. 
The barometer and thermometer were recorded seven 
times in the twenty-four hours for the whole thirty-five 
Months, and hourly one day in each month. On three days 
in each month, one of these being the sogallr Scere M9 
