the apparatuses in fig1 to 3 are more particularly designed for evaluating the activity of the sebaceous glands . in fact it is known that , for any individual , a close correlation exists between the amount of sebum secreted by the skin on the forehead near the scalp and the greater or lesser activity of sebaceous glands . the &# 34 ; sebumeter &# 34 ; apparatus in fig1 comprises a box 1 , of generally cylindrical shape , which is open at both its ends . the axis of the casing 1 has been denoted by 2 . the casing 1 comprises two parts 3 and 4 , of different diameters , which are joined together by an annular shoulder 5 . in the smaller diameter part 3 of the casing 1 , a sample - holder 6 is mounted so as to slide along the axis 2 of the casing . when the sample - holder is not subjected to any compression , it normally projects outside the casing 1 . the sample - holder 6 is in the form of a cylindrical sleeve , the axis of symmetry of which approximately coincides with the longitudinal axis of the cylindrical casing and which is closed at its outer end by a frosted glass plate 7 . the frosted glass plate 7 is arranged perpendicular to the axis of sliding of the sample - holder 6 , which coincides with the axis 2 of the casing . the frosted glass plate 7 is detachably fixed to the sample - holder 6 by any suitable means , for example using a slide provided at the end of the sample - holder 6 . thus , the frosted glass plate 7 can be changed before each measurement step which consists of applying the said plate to the forehead of the person for whom it is desired to evaluate the activity of the sebaceous glands . a suitably calibrated compression spring 8 is fixed at one of its ends to the sample - holder 6 and at its other end to a ring 9 integral with the casing 1 and in this case coplanar with the shoulder 15 . in this embodiment , the force required to push the sample - holder 6 into the casing 1 is selected to be about 1 kg . in the larger diameter part 4 of the casing is a scale support 11 which can slide along an axis coincident with the longitudinal axis 2 of the casing . the scale support 11 is in the form of a cylinder closed at both its ends , inside which is housed an electric battery 12 for energising an illuminating lamp 13 . the end of the scale support 11 which is located opposite the frosted glass plate 7 is closed by a scale 14 on which a suitable reference mark 14 &# 39 ; is engraved . the scale 14 is illuminated by the lamp 13 carried by the support 11 , and the emitted luminous flux is reflected by two mirrors 15 towards the scale 14 . the lamp 13 is intended to emit a sufficient flux of yellow , white or green light to enable a user with average eyesight to read the scale easily . the scale 14 is approximately parallel to the frosted glass plate 7 . the end of the support 11 which is opposite to that where the rule 14 is arranged is closed by a circular wall provided with an electric switch 16 of a conventional type , which makes it possible to switch the lamp 13 on or off . the support 11 is integral with a slider 17 which travels along a rectilinear slot 18 located parallel to the sliding axis of the support 11 . the slider 17 can cooperate with a milled nut 19 which makes it possible to lock the translational movement of the support 11 inside the box . graduations 19 &# 39 ; are arranged along one of the parallel edges of the slot 18 dividing that edge into four zones of four different states of greasiness , to be indicated by pointer 19 &# 34 ;. the &# 34 ; sebumeter &# 34 ; apparatus which has now been described is used as follows : firstly the apparatus is pressed for about 10 seconds against the forehead of the person , preferably at the central part of the forehead , keeping the sample - holder 6 pushed inside the smaller diameter part 3 of the casing 1 so that the application is carried out under an approximately constant pressure . the sebum which is removed onto the frosted glass plate 7 has the effect of increasing the translucency of the plate 7 as a function of the amount of sebum deposited . the translucency of the frosted glass 7 is read by initially operating the switch 16 in order to illuminate the scale 14 , and then moving the support 11 until the pattern 14 &# 39 ; on the scale 14 appears visible and sharply defined , by virtue of transparency . it is then sufficient to record the zone of the graduated scale opposite which the slider 17 is located in order to characterise the activity of the sebaceous glands by a numerical datum . it is found that a close correlation exists between the values given by the apparatus in fig1 and those which are given by laboratory analyses . according to a variant of the device in fig1 it is also possible to arrange for the scale support to be fixed and to vary the illumination of the scale , for example , by varying the supply voltage of the illuminating lamp 13 by any known means , the translucency in this case being read by means of a voltmeter which enables the measured state of greasiness to be displayed . fig2 of the attached drawing shows yet another embodiment of a &# 34 ; sebumeter &# 34 ; apparatus according to the invention . this apparatus comprises a cylindrical casing 20 having an axis of revolution 21a . the casing 20 is closed at one of its ends by a circular wall 21b and open at its other end so as to allow the passage of a sample - holder 22 which is capable of sliding along an axis essentially coincident with the axis 21a of the casing . the sample - holder 22 is in the form of a cylindrical sleeve having releasably fixed to one of its ends a frosted glass plate 23 , used for sampling the sebum . the frosted glass plate 23 extends perpendicular to the sliding axis of the sample - holder 22 . a calibrated spring 24 connects the sample - holder 22 to a movable adjusting ring 25 which can be moved closer to , or further away from , the open end of the casing 20 by virtue of a helical cam slot 26 . the position of the movable ring 25 is adjusted so as to cause the sample - holder 22 to be pushed completely inside the casing 20 when a force of about 1 kg is exerted on the sample - holder . inside , near its end wall 21b , the casing 20 comprises an electric battery 27 which is used for supplying an illuminating lamp 28 . a switch 29 , provided on the end wall 21b , makes it possible to switch off and on a lamp 28 energised by the battery 27 . two diametrically opposite apertures 30 are made in the wall of the casing 20 . they are located perpendicular to the axis 21a of the casing and parallel to the frosted glass plate 23 and are intended to guide a longitudinally movable scale 31 . the scale 31 is in the form of a plate comprising a series of four reference marks 31 &# 39 ; which together define four different states of greasiness . these four reference marks 31 &# 39 ; can consist of any patterns of which the line thickness , for example , varies gradually from one reference mark to another , as shown at fig2 a . in order to use the &# 34 ; sebumeter &# 34 ; apparatus which has now been described , it is necessary to press the frosted glass plate 23 for about ten seconds to the central part of the forehead of a person for whom it is desired to know the activity of the sebaceous glands , this application being carried out under a pressure which is such that the sample - holder 22 is pushed inside the casing 20 . once this sampling operation has been completed , the lamp 28 is illuminated by operating the switch 29 , and the scale 31 is then slide across through the two guide apertures 30 so as to bring the four reference marks 31 &# 39 ; ( fig2 a ) on the scale successively opposite the frosted glass plate 23 . the higher or lower translucency of the frosted glass plate 23 is read by assessing which reference mark on the scale appears to be the sharpest . instead of slidable scale 31 , a scale can be used in the form of a circular disc 32 ( fig2 b ), which can rotate in a plane parallel to that of the frosted glass 23 about an axle 33 which can be snapped into u - shaped bearing clips 34 on the sidewall so as to be able to bring the four reference marks 35 successively opposite the frosted glass . the slot in the housing to receive disc 32 extends about 180 ° circumferentially , and can open downwardly . fig3 of the drawing shows a third variant of the &# 34 ; sebumeter &# 34 ; apparatus according to the invention . this apparatus comprises a cylindrical casing 40 having an axis of revolution 41 . the casing is closed at one of its ends by a cap 42 carrying a switch 43 . inside the other open end of the casing 40 is a sample - holder 44 which is subjected to the action of a calibrated spring 45 for a sliding movement along the axis 41 . a frosted glass plate 46 , used for sampling the sebum , is releasably fixed to the sample - holder 44 . the frosted glass plate 46 extends perpendicular to the sliding axis of the sample - holder 44 . two electric batteries 47 , which supply four diametrically opposite illuminating lamps 48 , are arranged inside a compartment located near the cap 42 , the switch 43 being used to illuminate and extinguish these four lamps . the essential characteristic of the sebumeter apparatus in fig3 lies in the configuration of the scale . the latter is in the form of a rotatable cube 49 , one of the axes of which is parallel to the plane of the frosted glass plate 46 . this cube is carried by two pivots 50 and 51 which are joined to the two opposite transverse faces of the cube . the two pivots 50 and 51 are located along that axis of the cube which is parallel to the frosted glass plate 46 . the pivot 51 extends outside the casing by means of a milled knob 52 which is used to rotate the cube . four reference marks , defining four different states of greasiness , are made on the side faces of the rotatable cube 49 . these four reference marks can advantageously consist of the numerals 1 to 4 and patterns of differing line thickness , only numeral 3 and its pattern being shown . the sebumeter apparatus in fig3 is used as follows : a frosted glass plate 46 is mounted on the sample - holder 44 and then applied for about ten seconds to the forehead of the person for whom it is desired to know the activity of the sebaceous glands . this step is carried out with a pressure of application which is sufficient to cause the projecting part of the sample - holder 44 to be pushed inside the casing 40 . once the sample has been taken , switching on the four lamps 48 in front of the cube causes them to illuminate the cube with a sufficient flux of light to enable the scale to be easily read . by operating the milled knob 52 , the user rotates the cube - shaped scale so as to present successively the four side faces , on which the reference numbers 1 to 4 are located , opposite the frosted glass plate 46 . the higher or lower translucency of the frosted glass plate 46 , onto which the sebum has been removed , is read by assessing which of the numerals 1 , 2 , 3 or 4 on the scale appears to be the sharpest . of course , the embodiments described above in no way imply a limitation and will be able to form the subject of any desirable modification without thereby going outside the scope of the invention .
apparatus for measuring the secretions of sebum of a skin sample of a living subject comprises a frosted glass plate spring urged to project from a casing . when pressed against the forehead of a living subject the frosted plate retracts yieldably to collect sebum under reproducible conditions . a reference scale inside the casing of the apparatus is illuminated from a known light source and is observed from outside by looking through the greasy plate . the sebum secretion is measured by changing the position of the scale , or changing the line thickness of a reference mark on the scale until a sharp , fine image of the reference mark can be seen .