There are many difficulties to be overcome in contriving a seat for reflectors on Alt-Azimuth stands : First, it is essential that in using it, the observer's legs should not be in front as on an ordinary chair, for it would then be impossible for him to approach his eye to the eyepiece in every position of the telescopes. Secondly, it is necessary that the seat should be moveable vertically to at least double the height of its lowest position; and, Thirdly, the height of the seat should be readily adjustable without the observer moving from it; and at the same time the whole thing should be quite simple and portable. The seat I have made attempts to comply with all these conditions. It consists simply of a saddle-shaped seat, attached to a frame sliding in a groove in two uprights, the height regulated by cogwheels and rackwork. The whole is constructed of well-seasoned oak, with the exception of the "saddle" which is of lime. The two uprights are firmly morticed into two horizontal bearers, braced together and strengthened by iron stanchions. The seat is of Lime wood, shaped and hollowed like a saddle, and the observer sits astride on it as on horseback. This "saddle" is fixed to what joiners call a "gallows-shaped bracket," firmly screwed to a frame sliding easily in a vertical groove in the uprights. Attached to this frame in front are two gunmetal racks, and at the top is fixed by iron supports, a curved oak bar like the back of a chair, which enables the observer to lean forward without fear of falling, and serves as a support for his arms in focussing, measuring, and observing with greater steadiness. The cogwheels are of gunmetal, and are fitted and keyed on an iron shaft working in front of the uprights. At one end of this shaft is an iron catchwheel which regulates the height of the seat. The bearers are braced together behind the uprights, and are left open in front, so that when the telescope is at its greatest elevation, and its most distant position in Azimuth, one angle of the tripodic stand of the telescope can be admitted between the uprights, and thus allow the observer to get up to the eyepiece-this being the position of the telescope most difficult for any seat to be used. The footrests are of iron and fixed to the uprights-they are moveable, and made on the principle of the rack-bracket on which a roasting jack hangs, having a round socket above and a square one below, so that when the seat is low down and they would be in the way, they can be easily turned inwards. (I should say that my reflector being of short focus, I find one pair of foot rests sufficient; but with a longer telescope, a second pair would of course be necessary.) To raise the seat when observing, it is only necessary to stand up on the foot rests and pull it up by the top bar; to lower the seat, it is easy to stand on the foot-rests and with the right hand release the catchwheel, the seat will then fall of its own weight; the height of the seat is thus most easily and readily adapted to the object under examination. The bearers rest upon small wheels in front, so that the observing seat can be run easily to and from the telescope. The whole seat is very steady and firm, the arrangement of the bearers forming two sides of a triangle, make it difficult to upset sideways, and they are sufficiently long to prevent any unsteadiness backwards or forwards. It is very comfortable and sufficiently portable. I find no difficulty in carrying it into the garden each night I observe. I am indebted to Mr. Browning for most kindly suggesting to me that it would be an advantage to have a small shelf fixed at the top of the frame under the curved bar, with holes pierced in it to contain the eyepieces mostly in use. Mr. Browning thinks also that if an upright iron bar were attached to one end of the curved bar, a light semi-circular frame of galvanized iron work might be made to swing on this, and after the observer had taken his place, he could turn it round and secure himself against the effects of wind-both very valu able suggestions which I shall endeavour to have carried out. I append a few dimensions : Uprights ... Ift. Ioin. *Height of seat at lowest position Height of seat at highest position Greatest elevation of eyepiece of telescope being 5ft. 11in. Burton-on-Trent : I am, Sir, yours faithfully, March 9, 1872. E. B. KNOBEL. P.S.-With regard to the cost of the above Observing Seat, I should perhaps mention that one of that size would be about £5, exclusive of making the patterns for the castings, the metal-work costing at least half the money. I did not aim at cheapness so much as simplicity and portability, but the expense might be much reduced by using other wood instead of oak, and also by having the cog-wheels and racks of iron instead of gun-metal, but they would not work so smoothly, and the seat would not be so durable. E. B. K. *A very trivial alteration in the position of one of the braces connecting the uprights would allow the seat to gc 14 inches lower. We have also received an observing chair suited for a refractor, the particulars of which will be seen among our advertisements. It is remarkable as to lowness of price. THE ECLIPSE EXPEDITION OF THE ROYAL ASTRO NOMICAL SOCIETY. SIR,-In common, I believe, with a very large number of those who crowded the meeting room of the Royal Astronomical Society on the night of Friday last, I went down for the express purpose of hearing the details of the results of the late Indian Eclipse Expedition. To my exceeding surprise and chagrin, not one syllable was said about it, save by a member of the council, who very pointedly referred to the conspicuous absence of those fellows who might reasonably have been expected to have been present, to have given us some information Why then, I would ask, have the society not been favoured with any account of the observations made by their own fellows? I see it stated in the public prints, that the expedition was sent out by the Government in the representation of the British Association. It therefore might possibly be conceived and urged that the observations made were the property either of the Government or of the Association. In the first case, of course, no one could deal with them, and they would probably be printed by the Admiralty; in the next, those who made them would have equally little control over their publication; and would have to keep them warm until the meeting next August, at Brighton. But, if I am rightly informed, there is a serial called Nature which has already contained reports of the Indian observations, and, unless I have curiously misread the newspaper, Mr. J. Norman Lockyer has been lecturing on this very subject at the Crystal Palace; so that, at all events, he treats his observations as private property. During the desultory conversation which ensued after the meeting broke up, it was hinted that the results of the late expedition are being There are many difficulties to be overcome in contriving a seat for reflectors on Alt-Azimuth stands : First, it is essential that in using it, the observer's legs should not be in front as on an ordinary chair, for it would then be impossible for him to approach his eye to the eyepiece in every position of the telescopes. Secondly, it is necessary that the seat should be moveable vertically to at least double the height of its lowest position; and, Thirdly, the height of the seat should be readily adjustable without the observer moving from it; and at the same time the whole thing should be quite simple and portable. The seat I have made attempts to comply with all these conditions. It consists simply of a saddle-shaped seat, attached to a frame sliding in a groove in two uprights, the height regulated by cogwheels and rackwork. The whole is constructed of well-seasoned oak, with the exception of the "saddle" which is of lime. The two uprights are firmly morticed into two horizontal bearers, braced together and strengthened by iron stanchions. The seat is of Lime wood, shaped and hollowed like a saddle, and the observer sits astride on it as on horseback. This "saddle" is fixed to what joiners call a "gallows-shaped bracket," firmly screwed to a frame sliding easily in a vertical groove in the uprights. Attached to this frame in front are two gunmetal racks, and at the top is fixed by iron supports, a curved oak bar like the back of a chair, which enables the observer to lean forward without fear of falling, and serves as a support for his arms in focussing, measuring, and observing with greater steadiness. The cogwheels are of gunmetal, and are fitted and keyed on an iron shaft working in front of the uprights. At one end of this shaft is an iron catchwheel which regulates the height of the seat. The bearers are braced together behind the uprights, and are left open in front, so that when the telescope is at its greatest elevation, and its most distant position in Azimuth, one angle of the tripodic stand of the telescope can be admitted between the uprights, and thus allow the observer to get up to the eyepiece this being the position of the telescope most difficult for any seat to be used. The footrests are of iron and fixed to the uprights-they are moveable, and made on the principle of the rack-bracket on which a roasting jack hangs, having a round socket above and a square one below, so that when the seat is low down and they would be in the way, they can be easily turned inwards. (I should say that my reflector being of short focus, I find one pair of foot rests sufficient; but with a longer telescope, a second pair would of course be necessary.) To raise the seat when observing, it is only necessary to stand up on the foot rests and pull it up by the top bar; to lower the seat, it is easy to stand on the foot-rests and with the right hand release the catch wheel, the seat will then fall of its own weight; the height of the seat is thus most easily and readily adapted to the object under examination. The bearers rest upon small wheels in front, so that the observing seat can be run easily to and from the telescope. The whole seat is very steady and firm, the arrangement of the bearers forming two sides of a triangle, make it difficult to upset sideways, and they are sufficiently long to prevent any unsteadiness backwards or forwards. It is very comfortable and sufficiently portable. I find no difficulty in carrying it into the garden each night I observe. I am indebted to Mr. Browning for most kindly suggesting to me that it would be an advantage to have a small shelf fixed at the top of the frame under the curved bar, with holes pierced in it to contain |