Remarks on the Trilobite. 25 
is sufficient to account for the 27 feet on ground so unequal as 
that of Quito. The 18 feet in the height of Bogota is so trifling 
a difference, that it rather proves the exactness of my calculation. 
In Popayan we have 99 feet ; yet the different barometrical meas- 
urements of that city differ still more widely. Caldas observes, 
p. 31, “'The Baron de Humboldt’s barometer stood in Popayan 
at 233.4, mine at 2211.2, and Bouguer’s at 2210.7.” The 
most accurate measurements of the peak of Teneriffe, selecting 
4 out of 14, leaves a difference of 71 French toises, or rejecting 
the barometric measurements of Borda, of 18 toises.—Hu ‘ 
Pers. Nar. v. 1, p. 160, 170. Saussure is said to have found 
water boil at 187° on the summit of Mont Blanc, being, accord- 
ing to Humboldt, 15,660 ft. It is 90 ft. only below the point on 
Pichincha, where 1 found it to boil at 186°. The elevations 
nearly equal the difference cannot amount to a degree; and I 
consider the error less likely to be on my side, because I was 
aware of the probable cause of error, and had to deduce the 
height from the accuracy of the observation. Humboldt in the 
same manner suspects the accuracy of Lamouroux’s observation 
on the peak of Teneriffe-—P. Nar. vol. i. p. 159. 
_ [To be continued.] 
Arr. Il.— Remarks on the Trilobite; by Jacos Green, M. D., 
Professor of Chemistry in the Jefferson Medical College, Phila- 
delphia. 
Remarks.—We are informed by the author that the present 
communication was written originally for this Journal ; but some 
peculiar cireumstances induced him to publish it (March 16, 1839) 
in the Friend, a weekly Journal of Philadelphia. By the author’s 
request it is now republished with additions.—Eds. 
Tue anatomical structure and physiological history of the 
Whole family of the trilobites are not only involved in great ob- 
scurity, but we can scarcely hope that the most persevering 
efforts of the naturalist will ever be able to penetrate the darkness, 
or unravel the mysteries, which involve the subject. No depart- 
ment in the science of organic remains has been pursued of late 
With more zeal and curiosity than this. The trilobite furnishes 
Vol. xxxvi1, No. 1.—July, 1839, bis. 4 
