when, in effect, the expectations from them were little more than the anticipations of what a voyage of discovery upon an unknown ocean might produce, -the propriety of embarking upon such investigations was thus unhesitatingly affirmed, how much more confidently may the duty of perseverance be insisted upon, when the results of the first experiment have already more than realized the hopes which caused it to be undertaken. They have indeed confirmed the belief that "the gigantic problem proposed to be resolved" is of a nature to yield in its full extent only to "continued and persevering inquiry;" but at the same time they may be said, in a certain sense, to have narrowed the field of inquiry, by showing more distinctly than was previously apprehended, both what is desired to be known, and how and where it is to be sought. If the history of magnetical science is to be something more than a fragment, the research must be persevered in. In considering the means by which the researches thus opened out may be most advantageously prosecuted, it is natural that we should look, in the first instance, to the adoption, at other selected stations, of arrangements similar to those which were instituted at the stations which were chosen for a first, and as it has proved, successful experiment; and with this view I may be permitted to restate the opinions which I submitted to the Magnetical and Meteorological Conference at Cambridge in 1845, as all that has since taken place has served to confirm them. "Before I close this communication, I wish to advert to the expediency of extending the system of observation now in operation at Toronto, St. Helena, and the Cape of Good Hope, to other of the British Colonies, where the same objects can be accomplished in an equally effective and economical manner. "In cases where the institution of similar establishments is strongly urged by the Governor of a Colony,-where competent persons are present and disposed to superintend the observations, and where soldiers of the Artillery are stationed whose services may be available, and whose employment has been shown to be economical and effective in a high degree in the execution of a laborious and exact routine of observation,-there is wanting only a supply of instruments, the temporary allotment of a building to contain them, -extra pay, such as the individuals at the above-named Observatories receive, and an authorized connexion with a head-quarter establishment whence they may derive instruction and guidance. "The cost of one of the Ordnance Observatories (including £100 a year for incidentals of all kinds) is £392 a year, exclusive of publication. It may be assumed that five years of hourly observation is a sufficient time of continuance for obtaining in any particular colony the mean values of the magnetical and meteorological elements, and their diurnal, annual, and secular variations, as well as the peculiarities of climate bearing on the health and industrial occupations of man. If the observations were printed in full detail for the five years, they would occupy two quarto volumes; but if it were thought sufficient hereafter that duplicate or triplicate manuscript copies should be deposited in different public libraries, and that publication should be confined to abstracts and an analysis, the cost of the publication would form but a small addition. "The colonies of Ceylon, New Brunswick, Bermuda, and Newfoundland are in the described case; their respective Governors are recommending the establishment of Magnetical and Meteorological Observatories in them; competent directors are on the spot [this was written in 1845]; and they are all Artillery stations." To the four stations thus named may be now added Mauritius and Demerara, as from both those Colonies, strong and repeated applications to the same effect have been sent through their respective Governors to the Secretary of State for the Colonies. Both these Colonies have offered to bear a portion of the expense of the proposed establishments; and have earnestly solicited to be placed in connexion with a head-quarter establishment, from which they might receive properly constructed instruments, with instructions and guidance in their use. Can it be said that we perform our duty as a mothercountry when we put such applications on the shelf?- whilst, in the interests of science, it would be difficult to estimate too highly the value of such institutions,-in forming good observers, who might subsequently extend their activity over a wider range,—in affording to travelling observers the opportunity of testing and correcting their instruments, as well as keeping up and perfecting their skill in observation, and in contributing to arouse, to nourish, and to extend to other parts of natural knowledge, that desire for the greatest pos2 I VOL. VIII. sible accuracy, which was formerly met with only in astronomy and in geodesical operations of the highest class. When it was first suggested that the officers and soldiers of the scientific corps of the army (Artillery or Engineers) stationed in the Colonies might, both beneficially to themselves and advantageously to the public interests, be made available for the performance of such temporary services, the suggestion, from its novelty, might have been open to many objections. None were, indeed, made by the military authorities of the time, who on the contrary approved and encouraged the proposition. There may have been doubts entertained in other quarters whether persons, whose ordinary occupations were so dissimilar, would be found to possess the necessary qualifications for carrying out a scheme of exact and varied observation, in which there was then no precedent to guide, and of which the performance would be sure to be extensively and closely scrutinized but such doubts, if they existed, have probably long since subsided, as the successive volumes of the Colonial Observatories have appeared. : One great and unquestionable advantage which future institutions of this nature will have over those whose duties are accomplished, will be found in the assistance they will derive from the Physical Observatory of the British Association at Kew, as a head-quarter Observatory, in which their instruments can be prepared and verified, the constants, &c. carefully determined, new instruments be devised as occasion may require, and tested by experiment before they are sent out for use, and to which practical difficulties of all kinds, which may present themselves to the directors, may be referred. The omission of a provision of this kind when the Observatories were first formed, was undoubtedly a great fault, which has been, and could only be, very imperfectly remedied by the Woolwich establishment, designed for a very different purpose, and insufficient even for the duties for which it was designed. There is another advantage (if it be one) which might attend the early prosecution, viz. the opportunity of consulting (if it were desired to consult) the experience of the person who has conducted, -and, as he believes, successfully conducted,-the first experiment, from its commencement now almost to its close; but this, in the course of nature, can only be available for a few years to come. The Colonial establishments were instituted at the instance of the Royal Society and British Association, with a more general concurrence and approval on the part of the cultivators of science in all parts of the globe than, it is believed, were ever before manifested in regard to any purely scientific undertaking; and with such a cordial and effective cooperation of the public authorities as is well deserving of being held in remembrance. It is for those two great scientific bodies to consider whether any, and what, steps should now be taken to procure the continuance of the researches. March 12, 1857. Major-General SABINE, Treas. and V.P., in the Chair. The following communications were read :— I. "On the Immediate Principles of Human Excrements in the Healthy State." By W. MARCET, M.D., F.C.S., Assistant Physician to the Westminster Hospital. Communicated by H. BENCE JONES, M.D., F.R.S. Received February 23, 1857. (Abstract.) In a previous paper I had the honour of communicating to the Royal Society the results of a first series of investigations on the immediate principles of the fæces of man and animals; since then I have continued my researches on human excrements, being most ably seconded by my assistant, Mr. Frederick Dupré, Ph.D. The new results obtained were the following: : 1. Margarate of lime, phosphate of lime, and margarate of magnesia were discovered to be immediate principles of human evacuations. 2. I found a new method for obtaining excretine, and its chemical formula has been established. 3. The fact that vegetable food induces the presence of margaric acid in excrements has been confirmed. 4. The existence of a comparatively large quantity of cholesterine in the spleen, which I had mentioned before as probable, has been confirmed. When human fæces are exhausted with boiling alcohol, the fluid being rapidly strained through a cloth, a clear extract is obtained, which, on cooling, yields a deposit; this substance, being collected on a filter, is partly soluble in boiling alcohol, and there remains undissolved a residue insoluble in ether and alcohol. The residue in question being boiled with a solution of potash, dissolves almost entirely, and the addition of hydrochloric acid induces the formation of a precipitate in the solution. On examining this precipitate, it was found to consist of a crystallizable substance fusing at 60° Cent.; its structure and other properties were precisely those of margaric acid. The acid filtrate contained phosphoric acid and lime. From several quantitative analyses, I concluded that there was more lime than is required to combine with the phosphoric acid in the form of the neutral phosphate, the excess of lime being exactly that which was necessary to convert the margaric acid into a neutral margarate of lime, C34 H33 03+ CaO. Consequently it followed that the three substances existed in the form of margarate of lime and phosphate of lime as immediate principles of human fæces. The alcoholic filtrate from the deposit being allowed to stand for twenty-four hours, deposited another substance, of a nearly white appearance, and which proved to be margarate of magnesia. The peculiar action of a vegetable diet on human fæces was investigated by means of experiments undertaken upon myself, when I observed that an entirely vegetable diet was attended with the formation of a large quantity of margaric acid in the excrements,-most probably not in the form of a margarate, but in the free state, inasmuch as it was obtained from the decomposition, with hydrochloric acid, of the precipitate induced by adding milk of lime to the cold and clear alcoholic extract of fæces, after the separation of the abovedescribed deposits. In the month of December 1855, I had an opportunity of noticing that during a cold night, when the temperature falls below the |