blanch it by preventing the formation of chlorophyl. This, acting through the short period that any one attachment will suffice, can be overlooked as of little consequence. The simplicity of the machine, together with its accuracy and easy management, renders it capable of meeting all the requirements of the students of periods and rate of plant growth.

The accompanying cut of the completed instrument, Plate XXI, conveys a better idea than could be obtained from the most careful description. By the letters upon the several parts their uses can be determined. A is the base, made in one casting and so backed up by ribs as to prevent easy breaking or warping in cast. The advantage of the whole instrument standing on a single base is obvious at once. It not only insures s'ability in the structure, but prevents errors in the records that result from the least jar of either of the parts, when the index and recording drums are on detached bases. The index is always in the same relation to the record sheet, i. e., it is not possible for the index pointer to be a greater or lesser distance from point E., the fulcrum. The recording drum, which in this case is represented at B, is 24 inches in circumference, and is turned by a clock in the box marked C., so that it marks one complete revolution each 24 hours. This slow movement gives the record of each day in the form of a platted-curve, as shown on the record sheet. The ordinates to the curve are them selves curves, because the line itself is described by a falling body, which in its course marks out the arc of a circle whose centre is E. For all practical purposes and to maintain simplicity, stability and ease of adjustment, a simple lever has been kept for the recording arm, instead of the complicated link motion which would be necessary in order to cause J to fall perpendicularly instead of through a curved path. The cvlinder, B, is set upon a friction bearing of the clock, and is easily lifted from its seat by allowing the long bearing, K, to pass through a hole in the cross-piece, and then by again lowering it, the bearing is released and the cylinder removed. The lever, D, is poised at E on pin point bearings and upon a universal joint, so as to allow freedom of movement in all direc

tions. A tension at G keeps the pen-point, J, constantly in contact with the surface of the recording drum. At II a single friction pin retains the wire which suspends the forceps, I, in any position desired, so that when it is desirable to run a continuous test upon the same branch by shortening the distance between H and I, the pen-point at J can be adjusted to the desired height on the recording drum. To obviate the annoyance of removing the cylinder, to wind the clock, a key with a shank long enough to reach through the cylinder has been provided, and by dropping it between the spokes of the cylin der the clock can be wound at any time without the least interference with the progress of the test.

The hours of the day are easily determined, and we have at a glance the variation in the rate of growth or in the periodicity of the growth of the plant. The accuracy with which these machines can be adjusted, and the reliability of the clocks used, render them the best suited to experimental purposes of any machine of the kind that it has been my privilege to note the workings of, or to use. In future construction a slight modifi cation will be made, which, however, in no way alters the plan or workings of the machine. The clock, instead of being placed upon the bed, will have provisions made to allow it to drop into a box, the surface of which shall be flush with the top of the base plate. This cannot be said to be a modification, only in that it allows of a more compact arrangement.

All records of tracings are made in ink, and can be filed the same as any other document, thus overcoming the objectionable features of smoked rods or paper. Smoked paper can be used by substituting a tracer for the pen point at J. Such records can readily be fixed by a solution of rosin in alcohol. The carbon is set upon the papers, and as soon as the alcohol evaporates, the sheet can be filed in a manner similar to any inktraced record sheet. The only advantage in an ink tracing is to abridge the process by doing away with smoking the cylinders and fixing after the record has been traced.

Another objection to the use of the smoked papers is the ease with which it is erased or blotted before being fixed.

Briefly stated, the advantages which may be claimed for the machine are--a record in ink in the form of a platted curve; a rigid base; ease and accuracy of adjustment and weight sufficient to hold it firmly upon its foundation.

L. C. CORBETT.

NOTE FILING.

A uniform system of note filing, simple yet complete, for Station use is each year becoming more and more of a necessity. As the work takes new divisions and becomes more continuous in its character, a very different problem is presented than that of the annual experiment. In extended work, covering a series of years, the exact or even approximate requirements of any division of the work cannot be foretold; hence, the necessity of a flexible or expansible note file. The first thing to suggest itself along this line is the card system, or something of a like nature, in which the cards are replaced by slips of convenient size. This is certainly a decided advance over the common ruled note book and ledger system, in which several entries must be made in various parts of the same book, if it be of any considerable size. Then, these large ledg ers or journals are unwieldy-they cannot be carried into the field, and are therefore merely interpretations from the actual field notes In this work of transcribing, error is almost a certainty. for no matter how careful or accurate the workman, the change of an adjective, or the omission of a punctuation mark, may be sufficient to alter, or even absolutely reverse the meaning of a sentence.

One of the prime objects then to avoid, is the necessity of copying from one book to another. If there were no other advantages to be gained, the lessened cost of record keeping would in itself be sufficient to claim careful attention.

Another aim in view is a system of note filing which shall be without limit, and which shall not have that objectionable feature of the slip system-the loss or misplacement of slips.