240

CALCULATING MACHINES, ASTRONOMICAL INSTRUMENTS, Arc.

[Class X.

and highly important application by T. H. Henry, Esq.,F.R.S., as shown in the coating beams of balances withplatinum and palladium.

Chemistry and chemical apparatus need not detain uslong—the Exhibition presenting little (in Class X.) that isnew, excepting the application of the former to the extin-guishing of tire by Mr. Phillips (Class V., 92, p. 222),who has successfully brought this element under ourimmediate control by the agency of carbonic-acid gas,nitrogen, and aqueous vapour. His contrivance, by whichthese agents are evolved, differs materially in its actionfrom that of water, which simply cools the burning sub-stance to a temperature too low for the existence ofinflammable gas, but does not at all interfere with thecurrent of fresh air, every accession of which is attendedwith a fresh increase of combustion. The chemical agentsconstituting the gaseous vapour generated by this machine,on the contrary, are highly inimical to fire, chiefly fromthe fact of their entirely preventing all access of pure airto the burning mass. There is another patented applica-tion of this kind, but we are ignorant of its details andapplication.

The Planimeters exhibited claim some attention, therebeing several ingenious machines of tins kind adapted tothe determination of areas of plane surfaces by mecha-nical means.

There are several exhibitors of air-pumps, who haveexercised much ingenuity.

There arc various machines for standard measures oflength exhibited, two of which are extremely beautiful.

Calculating Machines claim some attention as a mecha-nical power by which the hand is made to do the workof the mind; and operose and long calculations, requiringmuch strained attention, are performed by turning ahandle. Two such machines are shown, which performedwell and accurately.

We cannot help recording how clearly the injuriouseffects of patent enrolments on science were shown in thecourse of our labours ; many of the ingenious contrivancesexhibited proved to be merely variations, for the avoid-ance of the infringement of patents. In many cases thesubjects patented were of a very trifling nature, but stilltheir effect was to shut up the path in that direction fromfurther improvement. The great advance of photography,previously alluded to, and the perfection of the micro-scope, are chiefly due to the avoidance of patents in con-nexion with their improvements.

It was found that the instruments exhibited were, forthe most part, collected without any concurrence on thepart of the exhibitors, for the representation of the stateof science in their respective countries, and that thereforeit was useless to examine the instruments of each countryseparately. In the following Report we have, therefore,classified the instruments according to their use, includingthe contributions of all nations.

It is but right to say that some instruments inserted inthe Catalogue have not been found, and that in othercases neither the exhibitor nor any explanation of theinstrument were to be met with.

We now proceed to describe the several instruments ineach class.

Astronomical Instruments.

It is to be lamented that this department of the Exhi-bition contains results of the labours of but few indivi-duals ; and of large instruments, with the exception ofthe great equatorial by Ross, there is not one. This cir-cumstance, how much soever a matter of regret, is notone of surprise;—the risk of injury-and difficulty of car-riage being in some cases almost insurmountable, and thesame obstacles existing in full force, with regard to theexhibition of the large class of instruments termed port-able. When we consider that, in addition to the aboveobstacles, the risk of transmission and danger attendantupon removal must necessarily be great, and the involvedexposure highly hazardous, the scarcity of instrumentsin the British, and more particularly in the ForeignDepartment, will be sufficiently accounted for.

But in those instruments which are exhibited, it ishighly satisfactory to find the greater part of them cha-

racterized by exquisite workmanship, and a steady advancein their construction.

In Mr. Ross’s great equatorial, it will be seen that hehas followed the example of the Astronomer Royal, byhaving every part of the instrument cast in as few piecesas possible, and has thus avoided all unnecessary screwconnections. The casting of this instrument, by Messrs.Kansoines and May, is a fine piece of work. The sameprinciple of casting has been adopted by Mr. Simms, wholias avoided various screw connections in the constructionof his instruments.

It is most gratifying to perceive that, small as is thenumber of astronomical instruments, the credit they reflectupon the artists is very great; thus, the instruments exhi-bited by Mr. Simms possess points of high interest, viz.,the conversion of the axis of the transit into a telescope;the modes of illuminating the wires and field of tele-scopes; the application of the principle of vertical collima-tion to the altitude and azimuth instrument by piercingthe vertical axis; the adapting the axis of an equatorialto the application of a level, &e.,- all of which must belooked upon as improvements, and cannot fail to be ofgreat sendee for the purposes of observation.

In the German instruments of Merz and Ertel there isexquisite workmanship, well maintaining the celebratednames of the makers of the Poulkova instruments.

The divisions of the Ertel instrument are beautiful;but works of this kind, performed by hand dividing, areoperose and distressing.

The practice of hand dividing in this country is nowalmost superseded by machinery. Mr. Simms’ instru-ments, for the most part, have been so divided. Theadvantages of this method cannot be better shown thanin the comparison of the time occupied by the division ofone of the instruments in the Exhibition, the far-famed“Westbiuy circle,” and the time now occupied in per-forming the same piece of work.

The graduation of the two circles of the Westburyinstrument occupied Mr. Simms, as he has informed us,nearly twelve weeks of six days each week, ami on anaverage, of eight hours every day. The work was per-formed by lamplight, in a room otherwise completelydarkened; and although practice enabled him, on subse-quent occasions, to accomplish similar pieces of work inconsiderably less time, yet he always found it to be anexceedingly anxious and oppressive labour. By the meansof Mr. Simms’ self-acting dividing engine,* the actualgraduation is effected in five hours, to which length oftime a period of about five hours is to be added, which isnecessarily occupied in the arrangement of the instrumentupon the engine preparatory to cutting the divisions.Thus, the same work is done within ten hours -whichformerly occupied from five to six weeks, not to mentionthe saving of wear and tear upon the constitution of theoperator. The divisions are found to be fully as accurateas those cut by the original process.!*

In the American Department, Mr. Bond exhibits theelectro-magnetic apparatus used successfully by the Ameri-cans, both for the purposes of geodesy and astronomy;this American invention promises to be a real improve-ment in practical astronomy, and will, in all probability,form a new era in astronomical observations.

Dollond (145, pp. 426—42S, and see Illustration). Avariation transit instrument. The horizontal circle is12 inches in diameter, on which is fixed a smaller circleof 7 inches diameter; each is divided to every 10', and thelarger circle has three verniers, reading to every 10". The

* This beautiful machine is described in the 15th volumeof the Koval Astronomical Society.

f The dividing the 8-foot mural circle at Cambridge,which Mr. Simms graduated on its pier, occupied him se-veral weeks : see the results of the examination of the di-visions in the ‘'Cambridge Observations” for 1S33; seealso the results of the examination of the altazimuth instru-ment at the Royal Observatory, “ Greenwich Observations.”1847 ; and also the results of the examination of the di-visions of the great transit circle lately erected at Green-wich, “Greenwich Observations” for 1851. Both theseinstruments were divided by Mr. Simms’ self-acting di-viding engine.