US3254421A

US3254421A - Method and apparatus for rapidly drying a sample of moist material

Info

Publication number: US3254421A
Application number: US236575A
Authority: US
Inventors: Elwood W Kielsmeier; Justin R Jellings
Original assignee: Oscar Mayer Foods Corp
Current assignee: Oscar Mayer Foods Corp
Priority date: 1962-11-09
Filing date: 1962-11-09
Publication date: 1966-06-07
Anticipated expiration: 1983-06-07

Description

June 7, 1966 E. w. KIELSMEIER ET AL 3,254,421

METHOD AND APPARATUS FOR RAPIDLY DRYING A SAMPLE OF MOIST MATERIAL Filed Nov. 9, 1962 2 Sheets-Sheet 1 IN VENTORS ELWOOD W. KIELSMEIER JUSTIN R. JELLINGS June 7, 1966 E. w. KIELSMEIER ET AL 3,

METHOD AND APPARATUS FOR RAPIDLY DRYING A SAMPLE OF MOIST MATERIAL 2 Sheets-Sheet 2 Filed Nov. 9, 1962 INVENTORS ELWOOU W. KIELSMEIER JUSTIN R. JELLINGS United States Patent $254,421 METHOD AND APPAilATUS FOR RAPIDLY DRY. ING A SAMPLE OF MOIST NIATERIAL Elwood W. Kielsmeier and Justin R. Jellings, Madison,

Wis., assignors to Oscar Mayer & Co., Inc., Chicago,

Ill., a corporation of Illinois Filed Nov. 9, 1962, Ser. No. 236,575 5' Claims. (Cl. 34-42) This invention relates to moisture analysis, and more particularly to a new and improved method and apparatus for the rapid drying of a sample of moist material.

It is well known to those skilled in the art of making moisture analysis or determinations that a sample of material, such as a sample of moist ground meat, for example, can be dried in a shorter period of time by shaping the sample in a very thin layer before subjecting the sample to a source of heat. Forming of the sample-in a thin layer permits more rapid drying because of the greater surface area presented when the sample is in this configuration and because the thickness of the sample in this configuration is very small thereby readily allowing heat to penetrate the same. However, the art has been confronted with the problem of maintaining the sample in this configuration during the heating of the same. When a sample formed in a thin layer is subjected to heat, the sample tends to shrink thereby reducing its surface area and increasing its thickness, thereby requiring a longer heating period for proper drying of the sample in the accurate determination of its moisture content.

Accordingly, it is one of the primary objects of this invention to provide a method for the rapid drying of a sample of moist material, which method includes the step of pressing the sample into the interstices of a section of screen, whereby the sample will maintain its shape even when subjected to relatively high heat.

It is a further object of this invention to provide a method for the rapid drying of a sample of moist material, which method includes the steps of pressing the sample into the interstices of a section of screen, heating the sample at a relatively high temperature for a relatively short period, and then heating the sample at a lower temperature fora longer period of time until the same has been dried. It is another primary object of this invention to pro vide an apparatus for the rapid drying of a sample of moist material, which apparatus includes means for maintaining the sample in a relatively thin layer during heating of the same.

It is another object of this invention to provide an apparatus for the rapid drying of a sample of moist material, which apparatus includes means for maintaining the sample in a relatively thin layer during heating of the same, and which apparatus includes automatic means for heating the sample at a relatively high temperature for a relatively short period and then heating the sample at a lower temperature for a longer period until the sample has been dried.

These and other objects and advantages of the invention will become apparent from the following specification wherein like numerals refer to similar parts throughout.

In the drawings:

FIG. 1 is a front perspective view of an apparatus for the rapid drying of a sample of moisturized granular material; 7

FIG. 2 is a partial side elevation and a partial vertical section of the apparatus shown in FIG. 1;

FIG. 3 is a perspective view of a screen adapted to receive a sample of moist material to be dried;

FIG. 4' is a perspective view of a sample support pan adapted to receive the screen shown in FIG. 3;

FIG. 5 is a section taken along the line 5-5 of FIG. 3; and

FIG. 6 is a schematic drawing of the wiring diagram of the apparatus of FIG. 1 showing the major electrical components thereof. The moisture content of a material is most often ascertai'ned by taking a sample of the same, weighing the sample, drying the sample for removal of the moisture, and then weighing the sample after it has been dried. Percentage of moisture is then calculated by subtracting the dried sample weight from the wet sample weight, dividing this difference by the Wet sample weight and multiplying by one hundred. The drying step requires the greatest length of time, and accordingly it is desirable to subject the sample to as much heat as possible to shorten the time requiredfor the performance of this drying step- As a further aid in shortening the time required for drying the sample, the sample is shaped into a very thin layer thereby permitting faster removal of moisture because of the greater surface area presented and because; of the ease with which heat can penetrate completely through the thin layer. Because the layer is very thin it has a tendency to thrink when subjected to heat, thereby decreasing the surface area and increasing its thickness. Manifestly, both of there factors make a sample more difficult to dry. The rapid drying method of this invention prevents shrinkage of the sample; it ineludes the step of spreading a sample of moist material into a thin layer and mechanically aflixi'ng the layer to means whereby the layer will be prevented from shrinking when it is subjected to heat. Further, the novel drying method of this invention includes the steps of initially subjecting the sample to relatively high heat for a relatively short period of time and then subjecting the sample to lower the heat for a longer period of time. More eiiective drying has been obtained by using this two step application of heat.

In describing the method of this invention reference will be: made to the drying of a moist material, such as ground meat, sausage batter or emulsion. However, it will be realized that this material is mentioned for purposes of illustration only, in that the method of this invention is readily applicable for drying any material adapted to be spread in a relatively thin layer, which material contains a liquid such as water.

More specifically, the novel. method of this inventionfor the rapid drying of a sample of moist material includes the step of spreading the sample in a thin layer on a section of screen and pressing the sample into the interstices of the. screen before the sample is subjected to heating. This mechanical attachmentof the sample to the section of screen prevents the sample from shrinking when it is subjected to heat. This step of pressing a thin layer of the sample into the interstices of a screen has been found to be so efl'ective that the sample may be subjected to relatively intense heat in a relatively short period of time, i.e.,, it may be subjected to conditions which would normally result in severe shrinkage to a sample dried under known prior art methods. Manifest- 1y, a moisturized sample which can be maintained in a relatively thin layer during drying of the same can be dried much more readily because of the greatersurface area that is presented and because the thinness of the sample permits the same to be easily heated throughout its entire thickness.

FIG. 3 shows a section of screen adapted to have a sample of moisturized material spread thereon and pressed into the interstices thereof, which screen is adapted to be received in a shallow sample support pan 11. The screen 10 and pan 11 are part of the novel apparatus of this invention which will be referred to hereinafter These two parts are preferably disposable in nature, and they may be made from any suitable material. FIG. 4 shows a sample of moist material, designated 12, which sample has been spread in a thin layer on the screen 10 and pressed into the openings in the screen. The result of these steps is the complete embedding of the screen within the thin layer of the sample thereby reinforcing the same and preventing the sample from shrinking or buckling when it is subjected to heat. Because the thin layer of the sample is pressed into the screen and reinforced by the same, the sample may be rapidly dried by subjecting the same to relatively intense heat in a relatively short period of time.

It should be realized that the method of this invention can be carried out by using foraminous means other than a section of screen. For example, a small plate could be used, which plate has a plurality of closely spaced openings therein allowing the sample to be spread in a thin layer on the plate and pressed into the openings of the plate. As another alternative, a flat plate could be utilized, which plate contains a plurality of closely spaced protuberances of suitable configuration. The sample could be spread in a thin layer on such a plate with the protuberances completely embedded in the layer of the sample which will prevent the sample from shrinking when subjecting it to severe heating. It will be realized that any suitable flat plate or the like to which a layer of the sample may be mechanically affixed and held in flush contact therewith could be used in carrying out the method of this invention.

The novel drying method of this invention also includes the steps of subjecting the sample, which sample has been spread in a thin layer on a section of screen or the like, to an initial relatively short period of relatively high heat and then subjecting the sample for a longer period of time to lower heat. This two stage heating has been found to more effectively dry a sample in a given period of time. The particular level of heat applied during the two periods or the particular length of time of the periods is not critical. Each of these factors is determined by, inter alia, the nature of the sample, size of sample, amount of moisture in sample, etc. By use of the method of this invention, the time for drying a sample of ground meat has been reduced to a very small fraction of the time required to dry the sample by ordinary oven drying methods. Generally, the duration of the initial period of high heat will be only a fifth or a quarter of the total drying time. The level of heat during the high heat period may be as high as twice the level of heat applied during the low heat period. Rather intense initial heating is feasible because the temperature of the sample cannot exceed the boiling point of water until the rate of evaporation of water from the sample falls below that at which heat input exceeds dissipation by evaporation. Preferably, before this occurs, the low heat period is commenced. The level of heat during the longer low heat period is preferably just below that at which sample damage, i.e., charring, occurs. It will be realized that the method of this invention permits the rapid drying of a sample without damaging the same. The prevention of sample damage is important since most often the sample, as in the case of meat products, must remain fit to be subjected to further tests.

An apparatus for carrying out the method of drying of this invention will now be described. The apparatus embodies a drier, generally designated 20, which includes a. generally cabinet-like structure including an upper chamber or oven 21 accessible by a door 22 hingedly secured at the upper edge thereof to the top of the cabinet. The door 22 is provided with a knob 23 and a window 24, which window permits contents of the chamber 21 to be inspected when the dryer is in operation.

The chamber 21 includes an electrically energized radiant heating element 25 mounted therein, which heating element is generally horizontally disposed and depends from a pair of rods 26 which extend horizontally from and are secured to a post 27 bolted within the drier. A wall 28 defining the rear end of the chamber 21 forms a compartment behind the chamber 21 for reception of a variable voltage transformer (not shown in FIG. 2), which transformer is controlled by a knob 29 disposed at the top of the drier. I

A frame 30 is slidably mounted on the floor of the chamber 21 and adapted for horizontal reciprocating movement from a forward position near the door 22 to a rearward position beneath the heating element 25. The frame 30 includes an inverted generally U-shaped plate 31, the downwardly extending ends of which are adapted to slide on tracks 32 secured to the floor 33 of the chamber 21. A plurality of generally horizontally extending arms 34 are secured to the horizontal portion of the plate 31, which arms are stepped upwardly where they project outwardly of the plate 31 and are provided with upstanding tips 35 adapted to engage the sides of the sample support pan 11 as will be referred to hereinafter.

Reciprocating sliding movement is imparted to the frame 30 by an endless chain 36 secured to the underside of the plate 31. The chain 36 is trained over an idler pulley (not shown) rotatably supported in a mounting block 37 and a drive pulley (not shown) driven by a reversible electric motor 38. A relay 39 is mounted in the lower portion of the drier just behind the reversible electric motor 38. A forward limit switch 40 is secured to the underside of the fioor 33, which switch has a rearwardly biased actuating arm 41 adapted to extend upwardly through an aperture 42 formed in the floor 33. A reverse limit switch 43 is also secured to the underside of the fioor 33, which switch has a forwardly biased actuating arm 44 adapted to extend upwardly through an aperture 45 formed in the floor 33. The actuating arm 41 is adapted to be engaged by the plate 31 when the frame 30 is in its forward position near the door 22 for opening of the forward limit switch 40, and the actuating arm 44 is adapted to be engaged by the plate 31 when the frame 30 is in its rearward position beneath the heating element 25 for opening the reverse limit switch 43. The function of these limit switches as well as the function of the relay and electric motor will be referred to in greater detail hereinafter in describing the operation of the apparatus of this invention.

The previously referred to sample support pan 11, shown in FIG. 4, is adapted to be detachably received in the frame 30. The pan 11 is supported in a generally horizontal position by the arms 34, and the pan is prevented from sliding from the frame 30 by engagement of the sides of the pan with the upwardly extending tips 35 provided on the distal ends of the arms 34. The pan 11 provides a convenient support for the section of screen 10, which screen is circular and has a diameter substantially the same as the inside diameter of the panll. After the screen shown in FIG. 3 is substantially embedded within a thin layer of a sample according to the method of this invention and as illustrated in FIG. 5, the screen is placed within the pan 11, which pan is then lowered into place on the frame 30 within the heating chamber 21 of the drier.

Referring again to FIG. 1, a high heat timer and a total cycle timer 51 will be seen to be mounted side-byside in the front wall of the drier just below the door 22 thereof. Both timers may be of any suitable type in which a plurality of contacts are provided and in which certain of the contacts are adapated to mak and break contact with other contacts after predetermined periods of time, which periods are manually set into the timers by manipulation of pointers 52 and 53'provided on the faces of the

timers

50 and 51, respectively

Appropriate scales

54 and 55, uniformly graduated in units of time, are provided for the pointers 52, and 53, respectively to indicate the length of time to which the timers have been set.

Also provided on the front of the drier 20 is a master switch 56 for energizing the various electrical components of the drier, a pushbutton 57 for commencing a timed drying cycle and a fuse holder 58 adapted to receive an appropriate fuse for preventing damage to any of the electrical components of the drier.

FIG. 6 is a schematic drawing of the wiring diagram of the drier 20 of this invention showing the major electrical components thereof. Referring to FIG. 6 and proceeding from the left side thereof, the electrical components schematically shown will be seen to include the master switch 56, the heating element 25, and a fuse 60, which fuse is adapted to be held within the fuse holder 58 shown in FIG. 1. A capacitor 61 is provided in a lead extending from the heating element 25 to the high heat timer 50 and to a variable voltage transformer indicated at 62. The pushbutton 57 is shown connected to the high heat timer 50 and the total cycle timer 51. A buzzer 63 is provided in the electrical circuit of the drier of this invention, which buzzer is in contact with the forward limit switch 40 and the reverse limit switch 43. The reversible electric motor 38 is, shown and it includes a forwardcontact 64 and a reverse contact 65. The relay 39 is shown adapted to establish simultaneous contact with the forward electric motor contact 64 and a contact of the forward limit switch 40 or the reverse electric motor contact 65 and a contact of the reverse limit switch 43. v

The operation of the drier of this invention is as follows:

A sample to be dried, e.-g., ground meat, is spread in a thin layer on the screen 10 and pressed into the interstices thereof until the screenis substantially embedded in the thin layer as illustrated in FIG. 5. The screen is placed in the sample support pan 11 and weighed. The support pan 11 containing the screen and sample is then ready to be placed into the drier for removal of moisture from the sample. At the beginning of thev cycle the frame 30 will be in its forward position in the heating chamber 21 with the plate 31 in contact with the actuating arm 41, thereby placing the forward limit switch in the open position.

The timers must now be set to the times desired. For purposes of illustration only and not for the purpose of limiting the apparatus or method of this invention, let it be assumed that it is desired to heat a ground meat sample for an initial period of two minutes at a relatively high temperature and then heat the sample for a longer period of time, say six minutes, at a lower temperature. In other words, a high heat time of two minutes and a total cycle time of eight minutes are desired. Accordingly, the high heat timer 50 will be set at two minutes by rotating the pointer 52 to the two minute line of the scale 54, and the total cycle timer 51 will be set at eight minutes by rotating the pointer 53 to the eightminute line on the scale 55. Next, the variable transformer 62 is set for the voltage desired by rotation of the knob 29 extending at the top of the drier 20. The purpose of the variable transformer 62 is for controlling the degree of heat supplied by the heating element 25 during the period following the initial relatively short period, in this case two minutes, which high heat is supplied by the heating element 25. The degree of the heat during 63 the initial or high heat period is not controlled by the transformer 62. The intensity of the heat during the high heat period is a function of the equipment used in the oven. Even though no means are provided in the embodiment of the apparatus shown for purposes of illustration, it will be readily apparent to those skilled in the art that a second transformer could be provided for varying the intensity of heat during the high heat period.

After the knob 29 has been set as desired, which will usually 'be at a setting to produce low heat just below the level which would result in damage to the sample being dried, the drier 20 is ready to be placed into operation.

The master switch 56 is now turned to the on position. Referring especially to FIG. 6, it will be seen that closing of the switch 56 supplies current to the heating element 25, high heat timer 50 and total cycle timer 51 for warming of these components. Full power is not at this time supplied to the heating element 25 for heating it to its level of maximum intensity. This is due to the fact that during this warm-up period power supplied to the heating element 25 is passed through the voltage transformer 62 which is set to supply power to the heater at a level considerably less than what it receives when operating at full intensity.

After completion of the warm-up period, which requires only a few minutes, the drier 20 is ready for. reception of the sample to be dried. The door 22 is opened and the support pan 11 containing the screen It) embedded in a thin layer of the sample is placed on the frame 30. The pan 11 rests in a generally horizontal position on the arms 34 and is prevented from sliding from the frame 30 by engagement of the sides of the pan with the upwardly extending tips 35. It wilI be recalled that at the beginning of a cycle the frame 30 is in its forward position near the door 22 withthe plate 31 of the frame in engagement with the actuating arm 41 thereby placing the forward limit switch 40 in the open position. After the support pan his in place, the door 22. is closed and the drier is ready for commencing a timed drying cycle.

Pushbutton 57 is depressed; this action produces simultaneous starting of the high heat timer 50 and the total cycle timer 51. When the high heat timer 50 commences its cycle, power to the heater 25 no longer flows through the variable transformer 62. Full power now flows directly to the heater 25 allowing the same to produce high heat at a level which is governed by designof the heater itself. Depressing of the pushbutton 57 also supplies power to the reversible electric motor 38 and the. relay 39. When the relay 39 is energized (the relay is shown in its energized position in FIG. 6) current will be allowed to pass to a contact of the reverse limit switch 43 a and to the reverse contact of the reversible motor 38. Accordingly, the electric motor 38 will be energized in its reverse direction thereby moving the frame 30 rearwardly in the heating chamber 21. frame 30 is moved away from the actuating arm 41 of the forward limit switch 40, the switch 40 will be closed. The reverse limit switch 43 will be in its closed position as the actuating arm 44 thereof has not yet been engaged by the plate 31 of the frame 30. With reference to FIG. 6, it will be noted that when the relay 39 in the position shown, i.e., its energized position, and with the reverse limit switch 43 in the closed position current will be supplied to the buzzer 63 for sounding of the same. The frame 30 will continue to move rearwardly by operation of the motor 38 in the reverse directionv thereof and the buzzer 63 will continue to sound until the frame 30 reaches its rearward position in the heating chamber 21 beneath the heating element 25. When this position-is reached the plate 31 of the frame 30 willengage the actuating arm 44 thereby opening the reverse limit switch 43. When this occurs power will no longer be supplied to the electric motor 38 or the buzzer 63.

When the plate 31 of the At the expiration of the two minute period during which the sample contained in the sample support pan 11 is subjected to high heat from the heater 25 the high heat timer 50 will again cause current to pass through the variable transformer 62 before it flows to the heater 25. This results in the supply of reduced power to the heater 25 for the remainder of the heating cycle. The level of heat during this period is determined by the setting on the variable transformer 62. The sample will then be subjected to' this reduced heat from the heater 25 for the remainder of the total time cycle, which time is governed by the timer 51.

At the expiration of the time set on the total cycle timer, eight minutes in the example used for purposes of illustration, the relay 39 will be de-energized. This will result in establishing electrical contact with a terminal of the forward limit switch 40 and with the forward contact 64 of the reversible electric motor 38. Since the forward limit switch 40 is in its closed position due to the fact that the actuating arm 41 thereof is not in engagement with the plate 31 of the frame 30, power will be supplied to the reversible motor 38 and the same will operate in its forward direction thereby moving the frame 30 forwardly in the heating chamber 21. At the same time power will be supplied to the buzzer 63 indicating that the frame and support pan carried thereon are moving within the'heating chamber. As soon as the frame 30 moves a short distance forwardly in the heating chamber, the reverse limit switch 43 will be allowed to close. When the frame 30 has reached its forward position near the door 22 the plate 31 of the frame 30 will again engage the actuating arm 41 of the forward limit switch 40 thereby opening this switch. Opening of the forward limit switch 40 will de-energize the motor 38 thereby bringing the frame 30 to rest in its forward position in the heating chamber. Opening of the forward limit switch 40 will also de-energize the buzzer 63.

The door 22 is now opened and the support pan 11 is readily lifted from the frame 30. If it is desired to dry another sample, it is only necessary to again place a new sample in the pan 11 and then replace the pan on the frame 30 and close the door 22. Depressing the pushbutton 57 will again commence another cycle of operation of the drier. If desired, the time settings can be quickly changed by manipulation of the pointers 52 and 53. Also, the level of low heat can be readily changed by rotation of the knob 29 which controls the transformer 62.

Thus it will be seen that by this invention a-novel method and apparatus have been provided for the rapid drying of a sample of moist material. The method includes the step of spreading the sample in a thin layer and mechanically affixing the layer to means whereby the layer will maintain its shape even when subjected to severe heating conditions. Themethod of this invention also includes the steps of initially heating the sample at a relatively high temperature for a relatively short period of time and then subjecting the sample to heat at a lower level for a longer period of time. This manner of heating has been found to be more effective in drying a sample than heating the same for a given period of time at a constant temperature. The drier of this invention permits the method of this invention to be easily carried out. The drier includes a section of screen adapted to be embedded in a thin layer of a sample to be dried and a support pan adapted to receive the section of screen. The drier includes a heating chamber for reception of the sample and timing means for automatically supplying heat to the chamber for an initial period of time at a relatively high temperature and then for a second longer period of time at a lower temperature.

While the invention has been shown in but one form it will be obvious to those skilled in the art that the invenmm is not to be so limited, but rather it is susceptible 8 of various changes and modifications without departing from the spirit and scope of the appended claims.

I claim:

1. A method for rapidly drying a sample of moist material comprising the steps of: spreading said sample in a thin layer over a foraminous member, pressing the layer against said member for filling the openings in the latter and thereby affixing the layer against the member, placing the member on a support in a heating chamber, heating the sample at a relatively high temperature for a relatively short period, and then heating the sample at a lower temperature for a longer period until said sample has been dried.

2. A method for rapidly drying a sample of moist material comprising the steps of: spreading said sample in a thin layer over a foraminous plate, pressing the layer against said plate for filling the openings in the latter and thereby affixing the layer against the plate, placing the plate on a support in a heating chamber, heating the sample at a relatively high temperature-for a period of time ending before the rate of evaporation of water from the sample falls below that at which heat input exceeds dissipation by evaporation, and then heating the sample at a temperature lower than that at which sample damage occurs for a period of time until said sample has been dried.

3. An apparatus for rapidly drying a sample of moist material comprising, a chamber having electrically actuated heating means mounted therein and a door on one side thereof for reception of said sample, first timing means in electrical contact with said heating means, a frame in said chamber operatively connected with a reversible electric motor for horizontal reciprocating movement to and away from said door, second timing means for actuating said electric motor, a horizontally disposed support member detachably received by said frame, a plate having a plurality of closely spaced openings there.- on removably mounted on said support member and adapted tohave said sample spread in a thin layer thereon and pressed into the openings therein.

4. An apparatus for rapidly drying a sample of mois material comprising, a chamber having electrically actuated heating means mounted therein and depending from the top thereof, which chamber has a door mounted at the front thereof for reception of said sample, first timing means in electrical contact with said heating means, a frame in said chamber operatively connected with a reversible electric motor for horizontal reciprocating movement from a forward position near said door to a rearward position beneath said heating means, second timing means for actuating said electric motor, a support pan detachably received in a horizontally disposed position by said frame, a section of screen removably mounted in said support pan and adapted to have said sample spread in a thin layer thereon and pressed into the interstices thereof.

5. An apparatus for rapidly drying a sample of moist material comprising, a chamber having electrically actuated heating means mounted therein and a door at the front thereof for reception of said sample, a variable transformer and first timing means for establishing electrical contact of the variable transformer with said heat-- ing means after a predetermined period of time, a frame .in said chamber operatively connected with a reversible electric motor having forward and reverse contacts, which frame is supported for horizontal reciprocating move ment between forward and rearward positions, a first limit switch in .electrical contact with said electric motor and adapted to be opened by engagement with said frame when the frame is in its forward position, a second limit switch in electrical contact with said electric motor and adapted to be opened by engagement with said frame when the frame is in its rearward position, a relay adapted to establish electrical contact with said first limit switch 9 and said forward contact or with said second limit switch and said reverse contact, second timing means for actuating said relay after a predetermined period of time, and sample support means being detachably received by said frame.

References Cited by the Examiner UNITED STATES PATENTS 1,080,198 12/1913 Cooke 34-53 1 0 2,470,266 5/1949 Richter 34-194 3,102,007 8/ 1963 Goldman 34-39 3,110,574 11/1963 Kodras 34-39 FOREIGN PATENTS 117,175 12/ 1899 Germany.

WILLIAM F. ODEA, Primary Examiner.

NORMAN YUDKOFF, Examiner.

2,391,441 12/ 1945 Baer 34-39 10 W. C. EVERETT, J. J. CAMBY, Assistant Examiners.