1881. 09 Trans. N. ¥. Ac. Scz. 
He also exhibited specimens of the blind fish (Amblyopszs sfelaeus), 
and blind crawfish (Cambarus felluctdus), and stereoscopic views of 
various points in the interior of the cave. 
(Abstract. } 
At the close of the Cincinnati meeting of the American Association 
for the Advancement of Science, in August last, he was one of a party 
of seventy-five members who visited the Mammoth Cave, remaining 
there two days, during which the greater part of the time was spent in 
exploration. He made no claim to new discoveries, but wished to call 
the attention of the Academy especially to recent observations, for the 
most part by Rev. H. C. Hovey, of New Haven, in regard to the tem- 
perature and structure of the cave. Mr. Hovey read a paper on this 
subject in Cincinnati, only a brief abstract of which has yet appeared 
in print, making use of a map, which is the first of its kind ever exhib- 
ited. The strictest precautions are observed by the authorities con- 
trolling the cave to prevent visitors from taking surveying instruments 
in with them: but the present manager, Mr. Francis Klett, has made 
a careful survey of the most interesting parts, and in time this will 
probably be given to, the public, though possibly the scale of measure- 
ment may be withheld. 
The central and right-hand portions of the map exhibited by Mr. 
Stevens had been enlarged by him from a copy of Mr. Klett’s map. 
The left-hand portion was drawn only from recollection of the localities 
traversed, and not to scale, being intended only to illustrate principles. 
The same remark applies to the vertical projection, the lettering of which 
corresponds with that of the horizontal projection. 
The temperature observations of Mr. Hovey were conducted with 
much care, and the very best instruments had been confided to him by 
the Director of the Winchester Observatory at New Haven. In 
August, 1881, while the external temperature at the neighboring hotel 
varied between go° F. and 100° F., at points farther than Ioo yards 
within the cave, the reading of the thermometer was never more than 
56° nor less than 52%°, the mean temperature being 54° for the 
summer months. At a point 1,000 yards within, a thermometer had 
been left for six months, including the autumn and winter, and daily 
visited by Mr. Klett, who reported the variation to be only from 54° 
down to 53°. The underground temperature in this latitude, for points 
60 or 70 feet below the surface, is usually assumed to be constant and 
about the same as the mean annual temperature above. According to 
Prof. Guyot’s maps, the isotherm of 60° passes about thirty miles 
south of the Mammoth Cave, while that of 50° passes about forty 
miles north of Cincinnati, The temperature of the Mammoth Cave is 
