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has much the appearance of a little ball of loose, yellow, or pale-brown silk. This, as well as others which occur now, often become pupæ in a piece of decaying wood, which must be supplied to those in captivity.

A portion of a decaying branch is easily obtained and laid upon the moss in the cage destined for them, and it is absolutely necessary for the successful rearing of some. Several singular larvæ of Geometræ, which resemble pieces of dead twig, may be found now on various bushes and in various situations. When at rest these so closely resemble the twigs on which they lie, that they are extremely difficult to detect by day. At night they are feeding on the leaves or are in various positions among the green foliage, to which they are a strong contrast, and they may then be easily seen. Sometimes, also, they

. are hanging from branches, suspended on silken threads, and are then conspicuous. Trees and bushes, as well as low plants, may be thus examined until the fall of the leaf and the commencement of winter.

FOURTEENTH ORDINARY MEETING.

ROYAL INSTITUTION, 17th May, 1858.

DR. INMAN, PRESIDENT, in the Chair.

DYCE DUCKWORTH, Esq., was elected an Ordinary Member.

DR. EDWARDS exhibited some living annelides, nudibranchs, and crustaceans taken at Hilbre Island.

The Rev. H. H. Higgins exhibited a fossil, resembling a Calamite, from Huyton Quarry, and added some stations to the local flora.

The following paper was then read :

EGYPT AND NUBIA: THEIR CLIMATE, CHARACTER, AND MERITS AS

A WINTER RESIDENCE FOR INVALIDS.

BY JOSEPH DICKINSON, M.A., M.D., F.R.S., &c. COMPELLED by illness to withdraw for a time from the active duties of an arduous profession, I endeavoured to regain health in a climate, brighter, dryer, and milder than our own, and visited in its search many of the most frequented and favoured places of resort both in England and on the continent of Europe, but in vain. I was then induced to try what the climate of Egypt and Nubia could accomplish, and here I found that which I had so long sought for. Having paid considerable attention to the character of this climate and its effect on myself and others, I propose briefly, though I fear very inadequately, to describe them, under the conviction that every trustworthy contribution, however small, will be considered by the scientific inquirer as tending to render more precise and accurate our knowledge of questions of great practical importance, and concerning which many erroneous views and false impressions prevail even among medical men.

The observations made in Egypt and Nubia were conducted by myself and my friend, Frederick Hubbard, Esq., C.E., conjointly. The instruments used were two selfregistering and two ordinary thermometers. One of the first was placed outside thg boat at the stern, and so situated as to be protected equally from the direct and the reflected rays of the sun, and from currents of air. The other self-registering thermometer was placed in a small dressing-room of the boat from which the sun was excluded, but the air freely admitted day and night. The other two thermometers were also protected as far as possible in the same manner. But, I believe, the temperature indicated by the thermometer is of necessity really, both by day and by night, above that of the air on the river. The walls of the boat radiate during the night some portion of the heat absorbed during the bright sunshine of the previous day, and thus, despite every precaution affect the thermometric results. These results were compared three times daily, and every precaution taken to prevent error and ensure accuracy. The importance of attending to these minute particulars cannot be over-estimated, and to its neglect may fairly be ascribed the discordant statements made by different observers.

My own observations in the Desert and Syria were too much interrupted and irregular to be of any scientific value, and I, therefore, gladly avail myself of the table kindly furnished me by my friend Mr. Hubbard, whose attainments in physical science are of the highest order. He had no self-registering thermometer, but took observations with an ordinary instrument with sufficient frequency to give the extremes of temperature with a close approximation to accuracy.

The table for Upper Egypt and Nubia is intended to exhibit at one view the daily maxima and minima of temperature (according to Fahrenheit's scale), the mean of the monthly maxima and minima, the monthly mean and the average range; the force and direction of the wind, the state of the weather with regard to clearness, haziness, dryness, fog, &c. The temperature in the sun is also given as compared with that in the shade, and that of the water of the Nile on the same day and in the same

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