On a Universal Indicator for Microscopes1856 - Microscopes - 8 pages |
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Common terms and phrases
accuracy accurate adjustment arranged axes and numbers black lead cator central guide lines corresponding dicator different impressions distance divisions employed enamelled cards engraved error fac-simile field of view Finder found front edge given glass cover graduated guide lines ruled guide piece hand vertical coincides highest powers horizontal guide line horizontal line horizontal series Indi Indicator by means Indicator is properly instrument intersect jects Judge A. S. Johnson kind of paper lection left hand vertical line G lower edge Measures in Albany microscope modification motion mounted moveable stage number of objects object-glass observing occupied ordinary form paper centre piece paper covered parallel placed position of objects properly centred recorded numbers recorded position register the position reproducible right hand vertical screws series of numbers shown in fig slide slight standard inch steel plate Superintendent of Weights tioned UNIVERSAL INDICATOR vertical axes vertical guide line vertical lines vidual convenience Weights and Measures
Popular passages
Page 7 - ... inch objective. The Indicator having been put to so many and such severe tests I feel no hesitation in recommending it as a means of scientific intercourse among observers, and as a means by which collections of microscopic objects may be registered, arranged, and catalogued ; and an index to the...
Page 7 - I may state that numerous mounted slides of minute recent and fossil diatoms have been exchanged through the Post Office by Judge AS Johnson of Albany, and myself, and that each has found by the ordinary as well as modified forms of the Indicator all the shells, however minute, fragmentary or previously unknown, which the other had recorded. Some of these objects were less than l-1000th of an inch in diameter, and yet they were found without difficulty by means of the Indicator.
Page 8 - Indicator, and therefore in consequence of unequal shrinkage a slight deviation is produced. The Indicator for use with the microscope is printed upon enamelled cards, and the different impressions have been found to agree so closely with each other as well as with the original plate that no appreciable error is perceived. I can not close...
Page 2 - Should it ever be desired to reproduce the Indicator by engraving or otherwise, the dimensions above given must be most accurately preserved. The dimensions here given were taken from the standard inch of the United States belonging to the State of New York and preserved in the office of the Superintendent of Weights and Measures in Albany. It is the same as the English inch. The slides on which objects are mounted to be used with the Indicator must have guide-lines ruled on their under side as shown...
Page 7 - T1TV7rth of an inch in diameter, and yet they were found without difficulty by means of the Indicator. To determine whether different impressions of the Indicator when made on the same kind of paper were comparable, a set of objects was registered successively by seven different impressions made on enamelled cards some of which were arranged with the ordinary paper centre piece, and others with the central guide lines ruled upon glass. The numbers being recorded for the objects when well centred...
Page 5 - ... changes. One of these consists in removing the paper centre piece, and replacing it either temporarily or permanently by a glass plate bearing lines at right angles to each other ruled very lightly with a diamond point, and so adjusted as to coincide with the prolongation of CD and EF through the centre. For all but the highest powers there is no objection to having these excessively minute lines permanently beneath the centre of the Indicator as they do not perceptibly interfere with the light,...
Page 1 - IN the Quarterly Journal of Microscopical Science, vol. i, p. 34, an ingenious contrivance for registering the position of microscopic objects is described by Mr. Tyrrel ; a modification of this, by Mr. Aymot is given in a subsequent number (I. c., vol. i, p. 301) ; and a still better arrangement for the same purpose, suggested by Mr. Brodie and applied by Mr. Okeden to his microscope, is described at p. 166 of volume iii. of the same work. The last mentioned device can scarcely be improved upon...
Page 4 - ... found on trial that slides of the standard size, whether paper covered or not, may be employed with the Indicator for the registration of all objects under a glass cover of a square inch in size, which is quite as large as is likely to be use'd. In using covering glasses of an inch square it will be found necessary to employ the horizontal numbers 0 to 50, and the verticals A, A', for objects towards the right of the cover, and the other axes and numbers for objects towards the left. For a portion...
Page 7 - ... account of slight inaccuracies of mounting. The stages can doubtless be constructed to give as wide a range for motion as required, which will do away with the first mentioned objection. The second may be removed by placing an Indicator upon the upper plate of the stage when the latter stands at 4£...
Page 4 - ... in Albany. In order to extend the use of the Indicator to all cases which are likely to occur, the graduation was arranged with reference to slides three inches long and one inch wide, while it will answer equally well for smaller ones. When these slides are not covered with paper, and...