Projection Apparatus Research Articles

Studies on Wisconsin Carp, 1. Influence of Age, Size, and Sex on Time of Annulus Formation by 1936 Year Class

IN 1936 there was an unusually large hatch of carp in the Four Lakes region near Madison, Wisconsin. Through efforts of the Wisconsin Conservation Department to control the carp in these lakes by seining, nearly all the large carp had been removed by the fall of 1938, leaving an almost homogeneous population-the 1936 year class-in the lakes. Since intensive efforts were likewise made to reduce this population with traps and seines, it was a relatively easy matter to obtain frequent samples of the 1936 year class in most months of the year. Growth of this dominant year class was followed over a four-year period in three of the four lakes-Monona, Waubesa, and Kegonsa (3843, 2034, and 3145 acres, respectively). For each fish it could readily be determined whether or not the current annulus had formed. The present study is based on an examination of scales from 4089 carp belonging to the 1936 year class. These scales were mounted on slides in glycerine jelly and studied at a magnification of 66.7 diameters by means of a projection apparatus.

Notes on Aproctella nuda sp. nov., a Filarioid Nematode from the Chimney Swift, Chaetura pelagica (Linn.)

In a study of the parasites of the Chimney Swift, Chaetura pelagica (Linn.), two of 72 birds collected from a chimney on the campus of Purdue University were found to be infested with a new filarioid nematode for which the name Aproctella nuda is proposed. One of the infested birds contained 13 worms, the other three. The parasites occurred in the mesenteries of the abdominal cavity. The nematodes were killed in hot glycerine-alcohol and mounted either in glycerine or glycerine-jelly after the alcohol had evaporated slowly. Some of them were mounted unstained while others were stained slightly with eosin, which, when added to the glycerine in very small amounts, was absorbed slowly by the worms. Microfilariae were obtained from the mature females by tearing the uteri apart with fine needles. The anterior ends of a few worms were severed and mounted vertically for observation. All drawings were made with the aid of projection apparatus and their respective scales are indicated. All measurements given below are in millimeters. Aproctella nuda sp. nov. Diagnosis.-Filiform worms with the characters of the genus. Both ends rounded; head without conspicuous lips or other ornamentation, mouth simple, with three papillae on each side. Cuticle smooth, small chitinous ring in mouth. Anus may atrophy. Male: caudal alae and papillae absent; length 9, width 0.10-.11, esophagus glandular, with no distinct divisions and 0.44-49 in length by 0.033 in width; spicules unequal and dissimilar; left spicule pointed and 0.062 long; right spicule 0.072 long and tip spoon shaped; cloacal opening 0.066 from posterior end; posterior extremity recurved ventrally. Female: length 15-19, width 0.20-.25; esophagus as in the male but 0.41-46 long, by 0.03-.05 wide; chitinous oral ring 0.013 in diameter; vulva posterior to esophagus and 1.29 from the anterior end; viviparous, the embryos forming first as indefinite globular masses, gradually becoming vermiform, and developing into unsheathed microfilariae without bristles; distended uteri may fill the entire body cavity of the more mature females; ovaries in the posterior portion of the worm, one slightly anterior to the other, extending forward, then backward, and again forward before narrowing to form the short oviducts which expand to form the uteri. Anterior ends of the uteri apparently fused, to form a single resultant uterus which turns posteriorly, extending a short distance postericr to the vulva before turning forward to join the vagina.

The Growth of Coenis horaria (L.), Leptophlebia vespertina (L.), and L. marginata (L.) (Ephemeroptera)

SUMMARY. The results obtained from the measurements of the growth in length of three Ephemeropteran nymphs are described. The nymphs were Coenis horaria (L.), Leptophlebia vespertina (L.), and L. marginata (L.). The measurements were made with a projection apparatus. The growth curves show that in winter Coenis does not grow, while in Leptophlebia growth continues. The factors responsible for this difference in growth appear to be food and temperature. Both Leptophlebia and Coenis are detritus feeders, but Coenis evidently requires a detritus enriched by the fragments of filamentous littoral algae. The renewal of growth in Coenis coincides with the increased growth of littoral algae and rise of temperature in spring. At this time the gut contents of Coenis contains large quantities of filamentous algae.

A projection apparatus for compounding harmonic vibrations

Apparatus is described by which two or more simple harmonic motions may be combined optically with any desired amplitudes and phases, and both Lissajous' figures and the combinations of a wave with one or more of its harmonics may be demonstrated. Light from a point source after successive reflexions from plane mirrors mounted to vibrate or rotate, is focused on a screen as usual, but the motion of the mirrors is controlled both as to phase and amplitude by intermittent currents obtained from a rotating interrupter.

Discussion on “Thermionic peak voltmeters for use at very high frequencies” and “The theory and design of hot-wire ammeters for frequencies of 25 to 100 megacycles”, by Prof. Fortescue, and “An improved form of response-curve projection apparatus”, by Mr. Reid, before the Wireless Section, 1st April, 1936

Discussion on “Thermionic peak voltmeters for use at very high frequencies” and “The theory and design of hot-wire ammeters for frequencies of 25 to 100 megacycles”, by Prof. Fortescue, and “An improved form of response-curve projection apparatus”, by Mr. Reid, before the Wireless Section, 1st April, 1936

An improved form of response-curve projection apparatus

The paper describes a combination of beat-frequency oscillator and cathode-ray oscillograph so arranged that the oscillator output is rapidly varied in frequency over a limited range without appreciable change in amplitude, and , after passing through the apparatus whose response curve is to be measured, is applied to the vertical deflector plates of the oscillograph, the horizontal deflection being proportional to the frequency.A frequency scale is obtained on the oscillograph by means of piezo-elecric crystals, so that the calibration of the instrument is unaffected by variations in supply voltages, etc.The variation of frequency is obtained by electrical means instead of by the usual rotating condenser, and the absence of mechanically moving parts renders the apparatus compact and portable.

The authors' replies to the discussion on “Thermionic peak voltmeters for use at very high frequencies”, “The theory and design of hot-wire ammeters for frequencies of 25 to 100 megacycles” and “An improved form of response-curve projection apparatus”

The authors' replies to the discussion on “Thermionic peak voltmeters for use at very high frequencies”, “The theory and design of hot-wire ammeters for frequencies of 25 to 100 megacycles” and “An improved form of response-curve projection apparatus”

An improved form of response-curve projection apparatus

The paper describes a combination of beat-frequency oscillator and cathode-ray oscillograph so arranged that the oscillator output is rapidly varied in frequency over a limited range without appreciable change in amplitude, and, after passing through the apparatus whose response curve is to be measured, is applied to the vertical deflector plates of the oscillograph, the horizontal deflection being proportional to the frequency.A frequency scale is obtained on the oscillograph by means of piezo-electric crystals, so that the calibration of the instrument is unaffected by variations in supply voltages, etc.The variation of frequency is obtained by electrical means instead of by the usual rotating condenser, and the absence of mechanically moving parts renders the apparatus compact and portable.

Discussion on the two papers “Thermionic peak voltmeters for use at very high frequencies” and “The theory and design of hot-wire ammeters for frequencies of 25 to 100 megacycles”, by Prof. Fortescue, and “An improved form of response-curve projection apparatus”, by Mr. Reid, before the Wireless Section, 1st April, 1936

Discussion on the two papers “Thermionic peak voltmeters for use at very high frequencies” and “The theory and design of hot-wire ammeters for frequencies of 25 to 100 megacycles”, by Prof. Fortescue, and “An improved form of response-curve projection apparatus”, by Mr. Reid, before the Wireless Section, 1st April, 1936

The authors' replies to the discussion on “Thermionic peak voltmeters for use at very high frequencies”, “The theory and design of hot-wire ammeters for frequencies of 25 to 100 megacycles” and “An improved form of response-curve projection apparatus”

The authors' replies to the discussion on “Thermionic peak voltmeters for use at very high frequencies”, “The theory and design of hot-wire ammeters for frequencies of 25 to 100 megacycles” and “An improved form of response-curve projection apparatus”

Outstanding Problems in Photometry

DR. J. W. T. WALSH gave a thoughtful address on “Outstanding Problems in Photometry” to the Illuminating Engineering Society on February 4. He pointed out that the advent of the gaseous discharge lamp has made the problem of heterochromatic photometry a very urgent one. It is well known that if two surfaces are judged to be equally bright by a number of observers with normal colour vision when the brightness is one candle per square foot, they certainly do not necessarily appear equally bright when the energy they emit is halved (Purkinje effect). Another class of photometric measurements which presents new and difficult problems is the photometry of projection apparatus, such as motorcar headlights, signal lights and similar devices. For such apparatus the conception of candle-power often becomes meaningless. The different optical elements produce beams for which the effective light centres are at such widely separated positions that there is no point that can be approximately regarded as the effective light centre of the whole. Dr. Walsh suggests two methods of attack. The first is to abandon candle-power measurements altogether and give a figure or figures for the illumination produced at a specified distance from the face of the projector. The other is to make measurements of candle-power at very great distances from the projector. In the case of a railway signal, this distance may be half a mile. This calls for the use of a telephotometer. A sensitive instrument of this type will probably in the future become part of the regular equipment of any photometric laboratory which has to deal with projection apparatus. In addition, problems arise in deciding what type of measurement is most appropriate in particular cases.

The British Film Institute

THE British Film Institute's second annual report, issued on October 1, records notable advances (long overdue) in its task of “furthering effective co-operation between those who make, distribute, and exhibit films on the one hand, and all who are interested in the artistic, educational, and cultural possibilities of films on the other”. The scope of its activities is indicated by the chapter headings: The Cinema for the Schools, Free Trade in Educational Films, National Film Library, Vouchers of Approval, Entertainment Panel, Dominions, India and Colonies Panel, Medical Panel, Scientific Research Panel, Summer Schools, International. Its regular publications comprise Sight and Sound, on sale to the general public at 6d.9 quarterly; a monthly film review on sale to associate members at 2d.; and news letters circulated to members. In addition, there are occasional leaflets of which the best known, No. 5, on projection apparatus and films for schools, achieved a circulation of nearly 10,000; another, No. 8, gives a full account of the National Film Library established by the Institute last July. A scheme has been worked out for the award by the Institute of vouchers of approval to films voluntarily submitted to it for examination and, as a corollary of this, expert and authoritative advice is given to producers before and during production. The Entertainment Panel has undertaken a systematic inquiry into the supply of suitable films for children's performances. The Medical Panel has compiled a catalogue of British medical films and will issue supplements from time to time. The Scientific Research Panel is collecting material for a report on the extent to which the cinematograph is, and can be, used in the advance of scientific knowledge. The first Film Summer School for teachers was held at Scarborough last August. Ten local branches, known as Film Institute Societies, have been at work during the year, at Becontree, Bristol, Brighton, Chichester, Leeds, London, Manchester, Liverpool, Belfast and Salford.

British Industries Fair

THE British Industries Fair, 1935, organised by the Department of Overseas Trade, is being held at Olympia and the White City, London, on February 18-March 1. This year the Engineering and Hardware Section is to be held at Castle Bromwich, Birmingham, not simultaneously with the London sections, as previously, but later, on May 20-May 31. The textile and furnishing exhibits will be shown at the White City and the general articles, other than engineering and hardware products, will be exhibited at Olympia. There are 1,550 exhibitors at Olympia and the White City, of which more than 750 are from London. There are again notable increases in the space taken and the number of exhibitors, compared with last year's figures. An indication of the remarkable growth of the Fair is given by the fact that the advance catalogue, which is issued in nine languages, runs to 684 pages, or about 152,000 words. The exhibits of products of scientific interest at the Fair again cover a wide range and reveal markedly the increasing use of scientific products, both materials and instruments, in the field of industry. The Committee responsible for the organisation of the united exhibit of scientific instruments is to be congratulated on the important display at Olympia of scientific, optical and photographic instruments. Microscope object-glasses of great refinement of construction; microscope projection apparatus; sound projection apparatus for cinemas, with suit-case sound sets for commercial and educational purposes; various forms of plani-meters; pocket cameras and aircraft cameras; distant-reading thermometers; geophysical apparatus for prospecting for gold, minerals and oil-these are but a few examples, selected almost at random, of the products that are being shown in this united exhibit. It is worth notice that, until two years ago, practically all the various forms of planimeters used in Great Britain came from abroad; and similarly, the particular geophysical apparatus referred to above was practically a German monopoly. It is good to note the enterprise of British scientific instrument manufacturers in these new fields.

The Testing of Visual Acuity: III. Types of Test Field and a Projection Apparatus

Three ways of securing the test field in making the examination for acuity are discussed:–the illumination of test characters printed on an opaque surface; the transillumination of test characters printed or otherwise impressed on a translucent surface; and the projection of the test field from a lantern slide. The conditions which should be satisfied in each of these ways are stated and the merits of the fields obtained are compared. A projection apparatus by means of which all the principles recommended in this and the previous papers of the series may be applied, is referred to and its features and advantages are briefly noted. From the Research Laboratory of Physiological Optics, Wilmer Ophthalmological Institute, Johns Hopkins Medical School.

The relationship between "speed" and "altitude."

Speed tests were given under conditions which involved the exposure on a screen of simple narrative material, the exposure times being experimentally varied by means of a projection apparatus. Altitude, or the difficulty level attained in a series of problems of increasing difficulty without time restrictions, was measured by scores obtained through the use of the completion elements of Thorndike's CAVD tests. In a group of 116 college students speed of mental processes was a negligible factor in determining the correlations between the test of altitude and the tests given under widely varying time restrictions. Mental ability is not contingent upon the speed of mental processes. Speed and altitude do not involve a marked community of function. (PsycINFO Database Record (c) 2012 APA, all rights reserved)

THE USE OF THE WILSON CLOUD CHAMBER FOR MEASURING THE RANGE OF ALPHA-PARTICLES FROM WEAK SOURCES

A large Wilson cloud chamber operated by a synchronizing mechanism similar to that used by Blackett is described. It is shown how, by the use of mirrors, it is possible to take two photographs of the whole volume of the cloud chamber with a single lens, which are equivalent to photographs taken by two cameras at right angles. The design of such a camera is discussed in detail. The photographs are examined by replacing the developed film in the camera and using it as a projection apparatus. The two images can be combined on a suitably oriented plate as one image the same size as the original track. The method is thoroughly tested by photographing glass fibers and by range determinations. The reduction of the track lengths in the chamber to α-particle ranges under standard conditions is discussed fully. It is shown that the interval between expansions must be made much longer than is customary if precision is to be attained in this reduction. The temperature in the chamber is carefully examined throughout the single cycle and repeated cycles to determine this interval and other thermal conditions of operation. The whole technique has been developed with the aim of utilizing as many tracks per expansion as possible for the purposes of range measurement.

Galvanometer Mirrors for Sound Recording

IN the variable width method of recording sound on film, a galvanometer is used in which a loop of metal ribbon, 0-005 in. broad and 0-0005 in. thick, is placed between the poles of a permanent magnet, a small mirror being cemented across the two arms of the loop. When speech currents from the microphone and amplifiers pass along the ribbon, the mirror vibrates and causes the reflected beam of light to traverse a narrow slit at right angles to the direction of motion of the film, and thus trace a graph of the sound waves. Since the upper limit of reproduction from the ordinary talking film projection apparatus is about 6000 cycles-per second, the natural frequency of oscillation of the galvanometer must be at least as great as this. The inertia of its moving parts must, therefore, be low. The mirror must be as light and small as possible. It should also be accurately surfaced and silvered in order to ensure uniform reflection. The production of such mirrors is an interesting piece of optical work involving manipulative processes on a different scale from that employed for the usual products of the manufacturing optician. Mirrors made by Messrs. Taylor, Taylor and Hobson, Ltd., Stoughton Street Works, Leicester, specially suitable for these galvanometers, are rectangular in shape and measure 0-032 in. by 0-018 in. by 0-004 in. The glass from which they are made is first cut to the correct size and then optically worked on both sides. The back surface is silvered by cathode sputtering and is protected by a suitable varnish. The finished mirror weighs 0-0001 gm.

Psychological Factors in Peripheral Vision.

Factors accounting for the great difference between peripheral and central vision are of three kinds. They are physical, such as the distortion of images from oblique rays, retinal, due to the distribution of rods and cones, and central, due to the interpretation of the images in consciousness. The present report describes the author's experiments to investigate these central factors. An apparatus was arranged in which an observer fixed a light through an aperture while objects were exposed at angles of 20, 40, 60 and 80° from the center of fixation by means of a projection apparatus. By means of a shutter, the time of exposure could be varied, but was usually one-tenth second. Six psychologists were used as observers for about 800 readings, the images exposed being drawn as accurately as the visual impression would allow. The figures used were geometric figures, combinations of circles and lines. As

Optical projection apparatus for schools

Optical projection apparatus for schools

THE MEASUREMENT OF CEREBRAL AND CEREBELLAR SURFACES

INTRODUCTION In previous papers, 1 a definite method was established for the measurements of the cerebral and cerebellar surfaces. At the time, it was felt that a more thorough understanding of the cerebral surface of man could be accomplished by comparative studies in various vertebrates, from the lowest to man. This paper deals with the problem. TECHNIC In the study of these measurements, the same method of technic was followed as outlined in our previous paper. In the search for methods to eliminate possible sources for error, a new projection apparatus was devised at the suggestion of Dr. Arthur Weil, which gave an enlargement of the sections from 30 to 100 times. Apparatus. —The apparatus consists of a modified Universal micrographic apparatus with a photographic mechanism removed (fig. 1). The apparatus consists of a