Wi 



AKT. 



DISPERSION. 



eitliv the limb u permanently fixed or new joint i under proem of 

 formation, lu the Utter case tin substitute U often batter than might 

 be expected ; Mid as this curious provision o( nature cannot be Un- 

 proved upon by art, it U batter to leave it alone. 



The most dangerous dislocations are thoee of the TertebnB or bone. 

 of the (pine, bnoau in that caw all the part* of the body below the 

 injury are paralysed. But the vertebra are eo curiously locked toge- 

 ther, and have singly to little motion, and are at the nine time to well 

 supported by ligament* and muscles, that they are seldom dialooated 

 iinlMi by a force auffieient to break u well as to displace them. Boon 

 an injury i almost always f.it.il. and instantly so in general win n it 

 take* place above the origin of the nerve* of respiration, that is, above 

 the fourth vrrtebne of the neck. The object of the executioner in 

 lijitg a criiuiiiAl is to produce this effect, but he more often fails 

 than succeeds. 



DISPART, the difference between the aemidiameter of the base 

 ring, at the breech of a gun, and that of the ring at the swell of the 

 muzzle. 



On account of the dispart, the line of aim or line of metal, which w 

 in a plane pasting through the axis of the gun, always makes a small 

 angle with the axis; so that the elevation of the latter above the 

 horizon is greater than that of the line of aim : an allowance for the 

 dispart is consequently necessary in determining the commencement 

 of the graduations on the tangent scale, by which the required eleva- 

 tion is given to the gun. 



The dispart, therefore, subtends, at the base of the gun, on angle 

 equal to that which, in a vertical plane passing through the axis of the 

 bore, would be contained between that axis and a line (colled the line 

 of metal) drawn from the circumference of the base to that of the 

 muzzle. In a 24-pounder gun, nine feet long for example, the dispart 

 U equal to 2735 inches, and the angle subtended by it is equal to '27' 

 nearly ; allowance must consequently be made for this value in point- 

 ing the gun by the Une of metal. 



In order to place the axis of the bore at any angle with a horizontal 

 plane, a " tangent scale " is employed [ORDNANCK] ; and in determi- 

 ning the graduations of this scale, it U manifest that the length of the 

 part raised out of the groove in the base of the gun should (the length 

 of the gun being considered as the radius) be equal to the tangent of 

 the difference between the number of degrees in the proponed angle of 

 elevation and the angle subtended by the dispart ; in order that, on 

 lowering the base of the gun till a line joining the top of the scale 

 and the top of the muzzle is parallel to the horizon (which may 

 be determined by a spirit-level on a rod laid from one of those points 

 to the other), the axis of the bore may be correctly elevated. Thus, 

 in the gun above mentioned, for an elevation of one degree, the scale 

 being raised up till the division marked 1* coincides with the top of 

 the base ring, the part raised should be equal to the tangent of 83' 

 only ; for an elevation of two degrees, the part raised should be equal 

 to the tangent of 1* 33' ; and so on. 



In some guns, however, such as the 8" and 10" shell guns, the 

 68-pounders, and some 82-pounders, where the line of metal would 

 give a Urge dispart, the inconvenience arising therefrom is avoided by 

 a dispart sight, a raised sight on the centre of the gun between the 

 trunnions which is of such a height that the line joining its top and the 

 notch in the base ring U parallel to the axis of the gun. 



DISPENSARY, an institution supported .by voluntary contribu- 

 tions for the supply of the poor with medical and surgical advice, and 

 with medicines gratuitously. Institutions of this kind are of very 

 recent origin. They differ from hospitals in this, that the sick, when too 

 ill to attend personally at the institution, ore sometimes visited at their 

 own homes by the medical officers of the charity. Each dispensary 

 indeed is restricted to a certain district, beyond the limits of which 

 the patients are not visited at their own houses. To every dispensary 

 there are always attached one, and sometimes two physicians; one 

 surgeon, and often a consulting surgeon, and a resident medical officer 

 who dispenses the medicines prescribed by the physicians and surgeons. 

 Every subscriber to the institution who jiays annually a certain sum is 

 called a governor, who is entitled to have at least one patient always 

 on the books ; a person who subscribes a larger amount in one sum is 

 called a life governor, who may have two or more patients on the list. 

 The medicines, which are commonly purchased in considerable quanti- 

 ties at a time and at wholesale prices, are dispensed in inexpensive 

 forms, anil in this manner the extent of the relief afforded is great, 

 while the cost is trifling. No other kind of charity affords so much real 

 assistance at so small an expense, and perhaps fewer objections apply 

 to this than to any other mode of giving eleemosynary aid to the poor, 

 lui peculiar excellence is that it enables the sick poor to Obtain advice 

 on the very first day of their ailment, and they are thus frequently 

 enabled to avoid a protracted illness. Even the great metropolitan 

 hospitals are often so full that urgent cases are constantly obliged 

 to wait days and even weeks before admission can be obtained ; but 

 by means of the dispensary poor families, and even the heads of 

 such families in regul..r <-niplyiiu-iit, may procure medical and 

 surgical assistance without leaving their occupation even for a day. It 

 would bo a great improvement in the principle of those institutions U 

 some i ii towards their mipj-Tt on the i>art of the poor them- 



selves were required to entitle them to av.iil themselves of the advan- 

 tages which they afford. TbU would remove the only objection that 



can be urged against such establishments, and- would enable the 

 independent labourer, without asking charity, to procure the best 

 advice for his sick family at a much cheaper rate than he can possibly 

 do at present. 



At the same time it should be recollected, that these institutions are 

 exposed to much abuse. The attendance of the medical officers being 

 gratuitous, there is a great inducement to a hasty and insufficient 

 attendance on the sick. On the other hand, a great number of persona 

 obtain relief at these institutions who could well afford to pay for 

 medical attendance. The only check upon these abusci would be the 

 payment of the medical officers for their services, who should be 

 responsible for the proper performance of their dnttattothe governors. 

 The governor too ought not to use these institution* for the benefit of 

 his poor relations or servants, but to take care that only those who 

 cannot afford to pay are recommended for relief. This was the 

 principle advocated by Mr. Smith of Sontlmm, in his self-supp 

 dispensaries. But unfortunately it met with little support or u- 

 couragement. Many of the clubs, or societies, particularly among the 

 Jews, are on the independent plan. 



DISPENSATION. The only kind of dispensation now used is that 

 l>y which the bishop licenses a clergyman within his juriMliction to 

 hold two or more benefices, to reside out of his parish, or dispenses 

 with some other particular of his strict duty. 



Dispensations formed a great source of the revenue of the court of 

 Rome ; for the (rape's dispensations prevailed against the law of the 

 country in many if not most instances, indeed hi all of an ecclesiastical 

 nature. This abuse was abolished in England by the statute 25 

 Henry VIII., r. -Jl ; and the power of the pope to grant dispensations, 

 not contrary to the law of Ood, was granted to the archbishop of 

 Canterbury under certain restrictions. It is under this general trans- 

 ference of papal jurisdiction that Lambeth dt'irea are granted. It is 

 hardly necessary to state, however, that this dispensary power is never 

 exercised in civil cases, and but in a few cages of purely ecclesiastical 

 cognisance, and in those the usage has become the law rather than the 

 exception. The right of the archbishop to grant special licences of 

 marriage, has been expressly recognised by the legislature. 



Formerly also the crown claimed a dispensing power, by which it 

 could exempt a person from the ordinary liabilities to the laws of the 

 realm ; the limits of which were never exactly defined. It was ex- 

 pressly abolished by the Bill of Rights on the accession of William and 

 Mary. 



DISPERSION. Light, as we receive it from the sun or from other 

 original sources, as a star, a fire, a caudle, &c., appears to the senses aa 

 a simple undecompoeable element by the intrumcutality of which 

 objects are perceived ; and as for the peculiar colours of bodies, we 

 naturally consider them, according to our early impressions, as belonging 

 to the bodies themselves, or inherent in them. We are partly un- 

 deceived in this view by the changing colours of birds' feathers, soap- 

 bubbles, &c. ; but we are enabled to trace the immediate cause of the 

 colours of bodies, whether permanent or transient, by the analysis of 

 light furnished by the well-known experiments of the glass prism. 



The triangular prism used for this purpose is a solid, terminated by 

 two equal and exactly similar triangles, and having besides three plane 

 faces of a rectangular form, contained by the sides of the triangles and 

 by right lines or edges joining corresponding angles of the two trian- 

 gular bases above-mentioned ; and any imaginary right line within it 

 parallel to these edges around which the prism U capable of revolving 

 is called the aru of the pram. 



In the annexed figure the triangle B A c represents a section of the 

 inm parallel to its basis or perpendicular to its axis : D E we shall 

 suppose to be a ray or exceedingly narrow beam of solar light in 

 from rantuin or air on the prism at E ; this ray of white light enters 

 the prism at that point, and having undergone refraction by the dense 

 medium of the glass, no longer proceeds as a simple ray E v. but is <lit- 

 jitned or divided into various rays of different colours over the space 

 nted in the figure by /KF, and emerging at/,F from the prism, 

 undergoes another refraction, such that the portion fy of the ray pro- 

 ceeding, from / is still more refracted than the portion ra from i : lit 

 n.iw thU dispersed beam gfro be intercepted by a screen or wall p K, 

 from which extraneous light is as much as |x>snil>li< (Deluded, v 

 th"ii tiiul tlrj elongated urucc ay brilliantly painted over with tints 



