Two Stoves, with Double Smoke-pipes, lighted at 6 A. M.

Fire taken off 9 A. M.

Hall Ventilators opened 1.30 P.M. Coals consumed, 70 lbs. NOTE.-The figures in italics show the amount of heat got from the large surface of heated iron after the fuel has been exhausted.

Single Stove with Double Pipes. Coals burned, 70 lbs. Stove lighted at 7 A.M.

* Fire taken off.

Various suggestions have occurred to me since these experiments were made for further improving the system, which I may shortly

mention.

1. As to the stove-room, it ought to be lined in the inner portion with some radiating metal or non-conducting substance, and be divided into two parts, one containing the bodies of the stoves or pipes, the other for firing, &c., a doorway being left between the two for the admission of such amount of air as required. And further, as the quick removal of the heat given off from the metal of the stoves or pipes is of importance, it is proposed to introduce a fan in the inner division to be worked from the outer, and to admit as small a portion of cold air as may be practicable for carrying off the heat into the hall or church.

From the result of these experiments I have come to the conclusion that for warming and ventilating buildings a stove-room is required, but the best mode of raising heat therein is an open question.

For large buildings I believe steam-pipes placed in the chamber would be the cheapest, the boiler being either in the chamber or outside. The heat would be greater than from hot water, but this latter would answer very well, and, perhaps, on the whole, would be preferable, the amount of heat being regulated by the extent of pipes; and it cannot fail to occur to every one that the result obtained from the above experiments of the effect of accumulated heat discharged into a building in the manner described would in all respects be preferable to the present system of pipes distributed in the building itself. It is a mistake to introduce heat into a church or hall by dispersing it in pipes covered with gratings; the waste of heat must be very great, while, if the same amount were accumulated in a chamber, and sent on, as described above, it will be distributed in a way so perfectly suitable to what is required, as to cause wonder that so valuable a property of heat had not long ago been known.

Ventilation.

The stove-chamber is itself an efficient means for the introduction of fresh moderately warm air, by simply opening the outer door and allowing the air to pass over the heated stoves or pipes, aided, if required, by using the fan. But the more important matter still

remains of getting quit of the vitiated air produced in crowded assemblies. This also formed the subject of experiment in the hall by my having temporary wooden tubes, 12 x 6 inches wide, placed along the walls about 6 feet from the floor, and discharging outside the roof. These, in a crowded meeting, were found to be very efficient in carrying off the vitiated air, though occasionally a backdraught came down; but were the discharge into a cavity above the ceiling, or an archimedean can at the opening, the back-draught would be avoided.

I have perfect faith in the efficiency of these wall-tubes in carrying off the vitiated air, and may mention an attempt I made for a visible proof of this. I burnt brown paper to produce smoke. The smoke ascended only a few feet, and then spread out horizontally in a cloud, and when near any of the tubes it was drawn up.

Remarks.

In Table No. II. the course of the hot air on entering the hall is pretty well shown. The larger portion, of course, mounts towards the roof, along which it travels at somewhat different temperatures. Not so, however, below where the audience sits,-there the gradually-rising temperature is practically equal in all corners of the hall, and that without any appreciable difference in time between the effects on the several thermometers.

2. Chapters on the Mineralogy of Scotland. By Professor Heddle. Chapter VI. "Chloritic Minerals."

In this Chapter, Dr Heddle discussed the substances usually thrown together, under the term of Chloritic Minerals. He showed, by an extensive series of analyses, that they were to be divided into three groups-those which occurred in metamorphic rocks, in recent strata, and in volcanic rocks.

He proposed to confine the term Chloritic to the minerals which are found in metamorphic rocks, and to apply the term, the Saponites, to those which occur in volcanic rocks.

In Scotland, metamorphic rocks afforded the species Pennina, Ripidolite, Chlorite, and Chloritoid. The New Red Sandstone of Elgin yielded Glauconite. Volcanic rocks contained, plugging up

their steam holes, Delessite, Chlorophæite, Hullite, Saponite, and Celadonite.

Of these, Delessite seemed to be confined to igneous rocks of Old Red Sandstone age-Chlorophæite and Hullite to more recent volcanics; while the others occurred in rocks of both of these ages.

He doubted whether the so-called Viridite of petrologists had any claim to a specific title-possibly it might be either Delessite, Saponite, or Celadonite. He regarded it as most probably the last of these. No attempt had been made to show that it was not an already named substance; and until there was good appearance of this, it was in no way entitled to a place in mineral nomenclature.

Two new minerals, belonging to the first of these groups, were noticed as occurring in granite near Tongue in Sutherland, and in Rubislaw quarry.

3. On Deep-Sea Thermometers. By Mr J. Y. Buchanan. For the purpose of observing the temperature of the waters below the surface in lakes and seas, two classes of thermometers have been used-namely, ordinary thermometers and self-registering ones. The earliest observations were made with the ordinary thermometer, and it was used in one of two ways-either it was sunk itself to the desired depth, and was so enveloped and protected by badly conducting material, that in bringing it up again through the layers of water of different temperature it had not time to alter its own temperature, or a quantity of the water at the desired depth was enclosed in a bucket of suitable construction and brought to the surface, and then immediately tested with the thermometer. Many very excellent and trustworthy observations exist which have been made in one of these ways. Our first knowledge of the temperature of the deep water of fresh-water lakes was obtained from the observations of Saussure on the lakes of Switzerland, made with a thermometer so padded and protected that it could be drawn up through 1000 feet of water of any temperature likely to be found in nature without sensibly altering its temperature. The self-acting bucket or seagange was used at an earlier date in the determination of the temperature of the deep water of the ocean. The accuracy of the

results obtained by this method depends greatly on the skill of the observer. In the case of Saussure and of Fischer and Brunner, the

VOL. X.

L

results are clearly to be relied on implicitly. In the experiments with the sea bucket, also, excellent results have been obtained. The results obtained by both methods of experimenting will be the more accurate the more uniform the temperature of the water. The temperature, especially of the bottom water, has also frequently been determined by bringing up a quantity of the mud, and taking its temperature when it arrives on board. This method also gives very satisfactory results when a considerable quantity of mud is at disposal.

Self-Registering Thermometers.-By far the greatest number of observations has been made with self-registering thermometers of one form or another.

The first self-registering thermometer was made by Cavendish.* He constructed both a maximum and a minimum thermometer, and they were of the kind called by the French à deversement, outflow thermometers. In fact, his maximum thermometer is in every particular identical with that known in France as Walferdin's; his minimum is on the same principle, but has a U-formed stem instead of a straight one. The disadvantages of this form of thermometer are two-namely, the indications are not continuous, but by jerks, depending on the size of the mercury drops, and they require to be constantly set, the maximum at a higher and the minimum at a lower temperature than the one to be observed; they also require constant comparison with a standard. They are, therefore, not suitable for use where many observations have to be made expeditiously.

In the year 1782 Six† published a description of the combined maximum and minimum thermometer which bears his name, and which has since continued to assert its place among meteorological instruments as perhaps the best self-registering thermometer. The instrument is too well known to require particular description. It may, however, be noted that Six himself did not use a hair for a spring to keep his indices from falling down, but a fine glass thread soldered to the top of the index, and sticking up in a direction very slightly inclined to that of the length of the index, so that it pressed gently against the sides of the tube. The advantage of the glass