in fathoms instead of giving them in feet, as in Map VII of the 'Rob Roy,' p. 338. Hence the error: the multiplication of 156 by 6, in order to turn fathoms into feet, gave me in fact 936 feet. I have informed the editors of it, so that it shall disappear from the next edition."
From this quarter the question is completely cleared up. There remains M. Lortet's observation on the exact value of which it is impossible to pronounce. "In spite of the fourteen years which have elapsed," writes the learned professor, "I remember very well that this cast of the lead, which astonished me so much, must have been made quite close to the place which I denote by the letter L on your sketch.[1] Unfortunately I did not verify it; the waves being enormous and the wind very high we were obliged to take refuge in Wady Semakh. But, I repeat, a single observation, made under such conditions, cannot contradict your measurements, which are so numerous and so precise."
Evidently it is quite possible that there may be a kind of very limited abyss at the point indicated by M. Lortet; quite recently M. Delebecque, the engineer, who occupies himself so actively with the hydrographic study of our French lakes, has described an abyss of this kind in the Lake of Annecey;[2] this well, called the Boubiôz, sinks abruptly more than 80 metres in the subsoil of the lake, while the neighbouring depths scarcely exceed 20 to 30 metres. I think, however, that more precise observations would be necessary to confirm the existence of a similar peculiarity in Tiberias.
In a general way, we may affirm that the Lake of Tiberias is not a deep lake, and that the depth of the water scarcely exceeds 40 to 45 metres, according to the season, the monthly variations being considerable enough, in consequence of the very active evaporation in this over-heated basin. The greatest depths are found in the axis of the Jordan and almost towards the meridian of the lake; the eastern side is steeper, the land being less extended there than on the other shore, and one reaches quickly enough depths of 25 to 30 metres.
The study of the temperatures of the lake comes to the support of what the soundings demonstrated to me. There will be found below the results of a series of thermometrical observations made by means of a Negretti and Zarabra thermometer, the frame of which was constructed by Dumaige, following the pattern adopted by Mr. Milne-Edwards on the "Travailleur" and on the "Talisman," and by H. H. the Prince of Monaco on the "Hirondelle."
I have also condensed in the form of a synoptic table the summary of my observations on the temperatures of the lake:—
