the embodiments according to fig1 to 7 have in common the clip legs 1 which are associated with the spring 2 for which force - application faces 10 are provided . furthermore all embodiments have in common the gap 3 between the clip legs 1 . it will be observed particularly clearly from fig1 that the dimensions of the gap 3 are fixed in all space - coordinates . the gap width 4 depends on the state of tension of the spring . it increases when the spring is in tension in order to return to a predeterminable value on relaxation of the spring which value corresponds to the skin fold drawn in between the legs . this skin fold is drawn into gap 3 across the whole breadth 9 to a height 6 . the juxtaposed faces of the clip legs 1 are then pressed directly against the skin surface in the relaxed state of the spring unless they are used , in the sense of the present invention to mount further sensors of measuring apparatus which would then engage with the skin . in fig1 the left clip leg schematically shows a mounted acceleration pick - up 18 . the relative distance of the teeth 7 which are provided at the extremities of the clip legs 1 is always less than the width 4 of the gap 3 so that the skin fold is effectively fixed . in the embodiments according to fig1 and 2 curved junction zones 8 are provided between the clip legs 1 and the spring 2 and their curvature is directed opposite relative to that of the spring 2 . in the embodiment of fig3 each leg 1 and spring 2 is connected by a junction zone which is of a bent configuration . in the embodiments according to fig1 and 2 these junction zones 8 touch one another along a line 17 which extends in the direction of the breadth 9 of gap 3 . on load application to the force - application faces 10 the junction zones 8 roll off on one another along this touchline and are thus able to open or close the clip legs . in the embodiment according to fig3 the junction zones 8 mutually penetrate as already described so that again the gap 3 will be closed when pressure is applied to the force application faces 10 . the embodiments shown in fig4 and 5 make use of an omega - shaped clip . here the clip legs 1 directly adjoin the spring 2 and merge terminally into outwardly extending foot portions which are capable of transmitting the application force of forceps 19 to the spring 2 . to this end the forceps 19 according to fig4 are provided with forceps tips 11 which are adapted to be inserted in matching holes or recesses 14 provided in the foot portions 12 . in modification of this arrangement fig5 shows an embodiment in which the foot portions 13 are bent back in the direction towards the clip legs 1 . this creates a space for the positive flush engagement of a blunt , headtype forceps tip 15 . the drawing readily shows that the transition from the foot portions to the forceps tips can be easily designed such as to achieve a very largely rounded - off configuration . lastly , fig6 and 7 show a particularly simple embodiment of the invention in which the clip is of u - configuration . the curved part of the u forms the actual spring 2 with adjoining rigid clip legs 1 . the latter , as shown in fig7 are provided either with juxtaposed teeth 16 on their inner sides or with teeth 16 of this kind on one side only whilst the other side is provided with one or more points 7 &# 39 ;. the clip is shown in relaxed state in fig6 and 7 . by introducing the tips of forceps into the clip and applying them to the force - application faces 10 this clip can be expanded in order to be set down in this state on the skin of the foetal head . the embodiments according to fig1 to 7 comprise conductor cables which , for the sake of simplicity , is actually represented in fig2 only . the conductor cable 20 is connected to the outside of one of the two clip legs 1 . next to the probe the cable 20 extends through , but insulated from in a known manner , a bright metal cylinder 45 to which latter the further cable 20 &# 39 ; is connected . in this way a reference potential is obtained which is in contact with the mother . besides these conductor means which are provided in all embodiments further sensors of further measuring devices may be provided , as already mentioned , fig1 schematically representing an acceleration pick - up 18 by way of example . instead of such a pick - up 18 there may be , in particular , electrodes for transcutaneous partial oxygen pressure measuring of the type described in the publication &# 34 ; cutaneous oxygen monitoring in the newborn &# 34 ;, paediatrician , vol . 5 , no . 5 - 6 , 1976 page 342 . likewise , a hall - or accoustic resonance generator 181 may be secured to the inside of one clip leg as shown schematically in fig1 by means of which it is possible to pick up movements relative to the magnetic field of the earth . such a hall generator is being offered under the type designation sas 231 l by the firm siemens aktiengesellschaft , erlangen , west germany . for a hall - generator of this kind , which would take the place of the acceleration pick - up 18 , five derivation conductors in all would be needed in order to provide the feed lines for supply voltage and the output lines for the output potential an illustration of this system in the drawings has been dispensed with in order to afford a clearer overall picture . however , they would come out on the free side of clip leg 1 . in the case of an acceleration - pick - up , on the other hand , four conductors would be sufficient . a suitable model carries the type designation ega - 125 - 500 and is supplied by the firm entran international fairfield , n . j . usa . with the aid of just three conductors a conventional microphone 184 such as shown schematically in fig1 could be fitted whereas a photo - optical device comprising a light source 182 and a photo - diode 183 as shown schematically in fig1 would require four conductor lines . the embodiment according to fig8 comprises angled portions 25 , 26 adjoining a v - shaped spring 24 and prolonged in contact points 21 , 22 . the angular position of these contact points 21 , 22 relative to the longitudinal axis 23 of the probe is such that in the compressed state of the v - spring 24 they have an inferior inclination relative to said longitudinal axis 23 than in the relaxed state of the spring . the dotted line 21 &# 39 ; illustrates the position of spring and contact point in the tensed state of the spring in the relaxed state the contact points adopt an almost right angle position relative to the longitudinal axis 23 . the v - shaped plastic sheath or envelope 27 comprises on both sides thereof forceps - pressure faces 28 , 29 which may be rendered even more efficacious by grooving , corrugations or the like thus it is possible to keep the v - spring closed by closing the forceps . in addition to the contact points 21 from which issues a joint output cable 31 , there is further provided a blunt electrode 30 in the vicinity of the tip of the plastic sheath 27 which is branched as mother electrode and from which issues the output cable 32 . the v - shaped sheath or casing 27 also encases the angled portions 25 , 26 . at this point the sheath comprises portions 33 and 34 which are flattened out in such a way as to limit the penetration depth of the contact points 21 , 22 . each section 33 , 34 carries a measuring element 35 , one of which is , for example , an ntc resistor . from each issues an output cable 36 , 37 . contact point 22 is furthermore constructed as an injection needle with an injection tube 244 attached thereto , as shown schematically in fig1 . optionally it could also accommodate the ntc resistor 135 with its output cable as shown in fig1 . in the embodiment according to fig9 like parts carry like references as in fig1 . however , here the plastic sheath 27 is not v - shaped but approximately circular in cross section . inside the sheath an output cable 31 , 31 &# 39 ; for each of the two contact points 21 , 22 is supported in insulated manner . moreover , the sheath also houses the two insulated cables 32 , 32 &# 39 ; of the reference potential which issue from the blunt electrodes 30 , 30 &# 39 ;. inside the plastic sheath 27 there is provided an integral plastic cylinder 40 extending in the longitudinal direction of the probe and accommodating a coiled compression spring 39 . the leading edge of the cylinder has an annular shoulder 41 which in the illustrated position is engaged by the opposite shoulder of the housing for a further measuring element 42 . in this position the further measuring element 42 is maintained by the relaxed coiled spring 39 in the free space 43 . thus the test probe according to fig9 is likewise in the application state . for the preceding stage of introduction the measuring element 42 was pushed back into space 43 thus compressing the spring 39 whilst the plastic sheath 27 was kept or held closed by means of forceps applied to the forceps pressure faces 28 and 29 . the load - relieving of these faces 28 , 29 thereupon caused the measuring element 42 to be pushed forward and at the same time caused the spreading out of contact points 21 , 22 . in other words , the further measuring element 42 is subject to the influence of the spring 39 while it is in function . this arrangement assures particularly effective skin contact . it will be understood that such a further measuring element need not necessarily be just a microphone but could also be , for example , an acceleration pick - up or a sensor for the determination of space co - ordinates , or a sensor for reflexion and transmission - measurements . transmission is possible when the contact points 21 , 22 are directly opposite one another beneath the skin . such measurements are of great interest for continuous monitoring because they allow valuable conclusions to be drawn concerning the blood circulation and thus acute changes in the circulatory situation such as for example centralization phenomena . light sources and photo - receivers for this purpose can be mounted in the region of the contact points . as already mentioned , at least one of the contact points may be a hollow injection needle as shown in fig1 . not only does this enable the connection of a tube or hoseline but such an injection needle may also be used to introduce a ph measuring electrode . such a measuring electrode 211 is known from the publication &# 34 ; innovation in instrumentation &# 34 ; by the firm world precision instruments , inc . new haven conn . usa , where it is more specifically called a beetrode . such a ph - measuring electrode can be very well guided and secured against breaking off inside a contact point of the hollow needle type . fig1 shows an arrangement in which the contact points 21 and 22 are provided at the extremities of a substantially w - shaped spring . this figure represents the state of tension . in the relaxed state the contact points 21 , 22 are spread apart and assume a fixed position in the skin of the foetal head which is pretermined by the relaxation state of the spring . in this state the inner section 44 of the spring is pressed in the direction towards the skin of the foetal head and presses the measuring element 42 against this skin .
a physiological test probe , in particular a vaginal electrode for the derivation of the foetal electrocardiogram , adapted to be transcervically fixed by means of points to the skin of the foetal head and attached to an output conductor cable . the probe may be a clip having a pair of planar parallel legs extending from a partially circular spring portion and having inwardly directed punctiform teeth on the free ends thereof , or may be provided with invasive contact points which are obliquely angled forwards from the longitudinal probe axis and ensure a good contact and as little damage as possible inflicted to the skin tissue of the foetal head . this probe is suitable for mounting elements associated with further measuring systems in order to allow remote instrumentally monitored observation of the birth process . the clip legs of one embodiment are mutually elastically connected and terminally provided with teeth so that on relaxation of the spring a skin fold is drawn into the gap between the clip legs and the skin fold is firmly held at a defined contact pressure .