How To Adjust Eyeglass Mountings. We slmll consider here two kind s of eyeglass moun tings in general, that is, those of the finger -pi ece type and those with the r egular hoop springs. In differentiating between these two kinds the spring of the r cgular and the bridge of the finger-piece mounting are tbe essential points and tbe same rules will app ly to both cl asses of mouutings except where tbey apply to these two conflicting portions. The first aim in fitting tbe eyeglass is to make it sta~· on securely with comfort, and in effecting this we cannot sacrifice correctness of position, so that many times we are confronted with a complex problem when we endeayor to make these three feature s work harmoniously. Let us first reason out the proper mean s of holding the mounting secnrely on the no se. Before we go farth er try this expe riment ,md get it impressed firmly upon your memory: Place the palms of your hand s together and admini ste r a slight press ure ; no tice when you do thi s that it requires considerable force to slide your hands apart. Now place the hacks of your hands togethe r and obserye how hard yon have to press to make it difficul t to slide your hands on each other. Why i s thi s so, It is so because in the case of your palms bei ng la id together the: presented a multiplicity of contact points, one fitted close ly into the other and they adhered to each other. 40 THE MECHAN ICS 01,1" FITTI NG GLASSES 41 A.pply this same sort of thing to the eyeglass guard and you haye solved both the problem of holding the glasses on securely and that of making it comfortable. The guards tbem selves must present a smooth s urface to the fle sh and must be curved so as to conform to the contour of the portion of the no se over which they rest. To curve tb e guards in this manner it is quite essential to have the proper kind of pliers; the best for this p urpose are tho se that have one convex blade and one concave so that by simply pressing the blades toether the portion of the guard on which you are working as nmes a corresponding cu rvature in degree depending on the amount of pressure you give the pli er s. By using pliers of this kind the guards may be accurately curved without interfering in any way with the r emaiuder of the guard or its general angle, etc. Suppose now after yo u haye giYen the guards the proper curvature and granting the other parts of the mounting are evenly balanced and straight, that one lens is higher than the other. This is a t rying puzzle to every beginner and to many who h ave been in the business a long time. ,Ve will say for instance hat the left lens is h igher than the right. Take the cur"l"ed pliers and bend the bottom of the left gnard out :-lightly, beiug careful not to bend it so fa r that it leaves the flesh. If this is not sufficient to lower the lens, bend the entire guard on its axis so that the bottom po rtion does not press so hard; this will bring the top of the a rd in tighter, but care mu st be exe rcised not t o briug this in too t ight. Further lowering of the left may be accompli shed by r aising the ri ght ienR, which is done by bending the right guard in toward the nose slightly at the bottom. It is surprising how bending of the guar ds 42 THE MmCHANI CS OF li'lTTI NG GLASSES will effect the respecti Xe heights of the len ses. As was said at the beginn ing sccurity, comfort and correctness of position must all obtain to the fullest po ssible degree aud one must not be sacrificed fo r the other s. In all cases the top of the guard should be curved out slightly to agr ee with the curvature of the nose a s it merges into the brows, if thi s cu rviug is not done here the top of the guard will cut into the flesh and prove , ery uncomfortable. It is the bottom of the guard that supports the weight of th e g la.sses and tile top tlmt prevenb them from ti lting over, so that the top of the guard mu, necessaril y press a trifle harder t han the bottom, and as a general thing more · pressure can be stood here tha!l at the bottom because there is nea rl y always a little cushion of fle sh h er e. ·Wherever the guard rest s on a bony part of the no se the contact mu st be very even and the pressure comparatively light, else the guard wi ll cut the skin. B y giving the guard s the same cur ve as th:nose they will stick to the skin and much less pressure will be required than other wise. Another good p la n is to bend the entire guard out from the back so that t here is more pressure along the front or outsi de edge of the guard than in the back ; this wil l cau se the flesh t o pile up slightly, as it were, in f ront of the guard and f orm a wedge of the fle sh whi ch p revents the mounting f rom slipping forward . In the case of a regular mou nting with the hOOI spring sometimes it is desirabl e to have the spring tilting slightl y at the top away from the forehead on account of heavy bro\vs or high nose. rll hel'e a r c sp rings that are made with this tilt but if the mouuting you are adjusting is not tilting a.nd you would prefer to ha,e it so THE MECHANICS 01' F ITTING GLASSES 43 you can yery easily bend it to have the desired til t. 'fo do this use what is known as stnd pliers, taking them in one hand a nd gripping the st rap of one of the studs with rhem. Grip the pliers tightl y and with the thumb of you r other hand press again st t he top of the spring and you ...-ill find that you can uend it outward. After doing this take hold of the other stud with the pliers in a similar way as befo re aud r epeat t he operation on t his side, thus e,·en ing up the tilt f rom both sides. It wili be w~ 1l to pract ice th is so that when YOll want to do it yon a r c sure that yon know what you a r c doing and it will p rove quite ,-alnable in getting a good {it mall )' times, for often the mount iug canDot be set far enough back on the nose due [0 prot ruding b rows. "l1eD placing eyeg lasses on a patient's nose do not. hold the glasses by placing your fin ge rs on the two sides of the lenses, but allow your fingers to touch only the edges of the lenses. T his keeps the lenses clean, eliminates the possibi lity of sticking your finger in the parient 's eye and is not so awkward as the other way. In handling finger-piece moun tings do not gr asp the ii::J er-pieces with the thumb and forefinger, but use the thumb and middle fi oge r and p ress the forefinger against the bridge ; this steadies th e mounting and gives you a ~ecure hold on it. Your patient.s shonld be in structed to ;ake hold of the mountings in the same mauuer. If the gua r ds are covered with shell, be sur0 to 3llooth off the edges all a r ound, using a fine, flat fil e for ilie purpose. It will often be found in cases where the mounting is not comfortable and th e gun rds a re cover ed ";th shell Or a similar substance that the trouble can be relie,-ed b~· filing the edges of the shell 011 the gua r ds. <4 THE MECHANICS OF F iTTIXG GLASSE>5 vVhen mountings con tain toric lenses the efficiene: of the lenses may be increased by bending the lenses in toward the temples. Thi s enables the patient to look sideways without being annoyed by the edges of the lenses. One of the chief objection s to finger-piece moun ina,; is that they ar e apt to sit too high and to sit farther f rom the face at the bottom of the lenses than at the wp. Great care must be exercised to prevent these two conditions and it will be well for you to understand ho,," - 0 overcome these difficulties. The standing away from e face at the bottom of the lenses can be r ectified by spreading the guard s at the bottom and by making them incline somewhat from the vertical. The custom of bending the ends of the bridge downward and drilling the holes aoo, e center is not advised in cases where it is desired to SE'the lenses lower, because it spoils the appearance of the mounting, narrows the base of the bridge and diSruP-5 the proper working of the springs and finger-piece5The better plan would be to fit mountings in which the guard-arms are so constructed that the guards may be rai sed without changing their angle or moun tings thaare supplied with drop-studs or "tangent" studs, as they are called by some. 'To increase the tension of s prin.,_ on finger-piece mountings detach the long end of the spring, gripping it with a pair of plier s, and p ull U.e spring tighter on the coil. To decrease the tension p1l5!: back on the coil. In cases of springs of the leyer , arie:in which it is not possible to adjust the tension of the coil, bend the long free end; to increase the tension be it toward the side it presses, to decrease, press towarC: the opposite side. THE MIDCHANICS OF FITTI NG GLASSES Pliers You Need. Fu ll Rou n d. Cutt ing. Half Round (Snipe Nose ) . Stud. 45 46 1' 1-lli.: .M ECHAN ICS OF l<'lT Tl,,"G GLASSES Concavo-Convex.. Ang lin g . Strap.