1846.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



153 



this pipe is firmly attacheJ to a vertical arm that passes through the lon- 

 gitudinal opening and attached to the leading or driving carriage of the 



Fig. 1. 



train, a portion of which is marked with the letter /. Fig. 2 represents a 

 transverse seciion of the apparatus taken through the line A B of fig. 1, in 

 which is shown the mode of closing the longitudinal opening hy means of a 

 Talve g sliding edgeways into a groove or recess formed in the upper part of 

 the tube. The operation is as follows : — At certain intervals along the line 



are to be erected steam boilers ; and in order to propel the carriages, steam is 

 to be admitted into the tube a a throughout the whole length, for the pur- 

 pose of warming the tube and driving out the air. The ends of the tube 

 and longitudinal opening being closed, a communication is to be formed 

 with the tube and a condenser, similar to those employed in steam engines, 

 for the purpose of condensing the steam, leaving the pipe empty or nearly 

 so ; when this is done the piston d d\% brought near to the opening leading 

 from the boiler, when a fresh supply of steam is admitted, which will have 

 the effect of propelling the piston and train of carriages along the line. 

 The specification states that the condenser may be dispensed with by open- 

 ing the cock rf, so as to let the steam first introduced into the pipe pass up 

 the funnel h for the purpose of driving out the air. i i is an arrangement 

 of levers for opening the valve d. In place of having stationary boilers, the 

 inventor proposes to have an ordinary locomotive boiler, and instead of the 

 steam working the engines as heretofore, such steam is allowed to pass 

 through the pipe e e into the main, either from behind or in front, depend- 

 ing upon the direction in which the carriage or train is to be propelled. In 

 descending inclines, the inventor proposes to fill the tube with steam, which 

 will have the effect of a break, the motion of the carriage being regulated 

 by opening the valve d so as to allow the steam to escape from the main a a 

 through the funnel into the atmosphere, k k (fig. 2) represents a covering 

 for the pipe, composed of felt, straw, sawdust, or other bad conductor of 

 heat. 



White Gravel. — Upwards of 7,000 tons of white gravel have been 

 sbipped from this city to Loudon since the 1 5tb of September last. It is 

 taken from the beach at Long Island, and used to beautify the parks 

 and gardens of London .—AVii- lor A' paper. 



A NEW GONIOIVIETER AND CRYSTALLONOME. 



At a recent meeting of the Chemical Society, Dr. Leeson read a paper 

 '' On crystalhii^rapliii, with a description iif a gfniiometcr tind crif^tutlonome, 

 or instrument for studi/ing cryslah, in reference totlieir gubernatorial aies." 

 The author commenced by observing that discriminative chemical researches 

 have not received that assistance from crystallography which might reason- 

 ably be expected from the natural distinction of form peculiar to various 

 different substances. 



The particular design of the author's present paper was to introduce 

 greater facility and simplicity in the classification and determination of 

 crystalline forms, both by improved methods of observation, and also by 

 a system of classification founded on the three gubernatorial axes, for the 

 happy discovery of which we are indebted to \\'eiss, by whom, however, 

 as well as by olhers who have succeeded him, systems have been proposed 

 by no means realising that simplicity and perfectiou of which the funda- 

 mental principle is believed to be susceptible. To prove that the nomen- 

 clature and classification of the dilferent authors were both confused and 

 complicated, various tables were referred to, showing the systems respec- 

 tively adopted by them. By referring to which it was apparent that dif- 

 ferent authors nsed the same terms for totally different fundamental forms ; 

 and also that by many of them terms were employed which, having reference 

 simply to the miinher of planes bounding a given system, were, in fact, as 

 subsequently demonstrated, applicable tu every class and order, and there- 

 fore not discriminative of any one in particular. Any one who may have 

 carefully examined the first crystals depositing from solutions of different 

 substances, will be struck by the general prevalence of the prismaiic or 

 hexahedral form, or of some modification thereof; at the same time, he 

 will observe great variety in the number of planes bounding many of the 

 crystals. Under the microscope he will not only be struck by the general 

 prevalence of parallelograms, or sections of the prismatic forms, as well as 

 hexagons, triangles, and other sections, resultiug from hemihedral modifi- 

 cations, but also by the primii facie similarity of the sectional forms pre- 

 sented by totally diflferent substances. It is in the discrimination of these 

 forms that the principles of classitication now about to be proposed, and 

 the goniomeier subsequently described, are peculiarly applicable. 



Before describing the system itself, the author requested to explain an 

 instrument which he exhibited, and stated he had contrived some years 

 ago, for the purpose of studying the relative character of crystals derived 

 from different positions and lengths of the three gubernatorial axes, and 

 for which instrument he requested to be allowed to propose the name 

 crystallonome. The author showed, with that instrument, that whatever 

 be the length and relative position or inclinalion of the three axes, a prism 

 or hexahedron must necessarily result from a set of planes terminating the 

 extremities of the respective axes, such planes terminating one axis, and 

 being parallel to the other two axes. These planes were represented by a 

 contrivance for attaching pieces of stiff paper or card-board to the extre- 

 mities of the axes. The author then showed that an octahedron must ne- 

 cessarily result in every case from a set of planes cutting all three axes, 

 and which octahedron might easily be built up and represented by threads 

 connecting the extremities of all the axes. The construction of other forms 

 was also demonstrated. 



The crystallonome, although constructed with only three zones placed 

 at right angles to each other, is nevertheless capable of showing the posi- 

 tion of the axes in every class, even where all the axes are oblique ; this 

 was illusirated by the iustrument itself. It was also shown, that whatever 

 be the class and order of a crystal, there are always two zones in which all 

 three axes will be fuuud. It having been already stated, that the three 

 gubernatorial axes form the basis of the proposed system, it w ill be evi- 

 dent that the discriminative iirinciples of the system must be dependent on 

 the position and length of the respective axes. Since the relative position 

 of the axes occasions the greatest difference in the appearance and character 

 of a crystal, it seems natural to take that as determining the class ; and we 

 shall find that as regards this distinctive charactLr, there are but three 

 classes to which the variation of position can give origin, viz. :— I, where 

 all the axes are situated at right angles to each other ; 2, in which one 

 axis is at right angles to the other two, which are obliquely placed as 

 regards each other, one rectangular axis and two oblique, being, in fact, 

 the same as thoush we represented it as two rectangular axes and one 

 oblique; 3, in which all the axes are oblique to each other. 



We have thus three classes, which we term respectively : — l.reclaugular; 

 2, right oblique ; 3, oblique ; and these we again subdivide into three 

 orders, dependent on the relative length of the axes, viz. : — 1, all the axes 

 equal ; 2, two axes only equal, the third being longer or shorter than the 

 other two ; 3, all the axes of different lengths. These orders we term— 1, 

 equiaxial ; 2, binequiaxial ; 3, inequiaxial. 



M'itb these three classes and three orders we obtain nine distinct crys- 

 talline bases, which, the author trusts, will be found easy to remember and 

 simple to distinguish. Generally speaking, few substances will be 

 found to crystallise in forms belonging to distinct classes or orders. 

 Without, however, passing any opinion on the subject of dimorphism, 

 the author showed, by reference to the native crystals of sulphur, and 

 also those obtained by fusion, that, according to the system now pro- 

 posed, sulphur cannotbe considered as dimorphous, the native crystals 

 being, in fact, modifications of the octahedrons, or the rectangular in- 

 equiaxial system ; whilst those of fusion are prisms or hexahedrons be- 

 longing to the same system. Both were exhibited to the meeting, and the 

 goniometer, subsequently described, applied to tlie measurement of the 



20 



