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2.1

1819,

Return of the mean annual strength of the garrison of Gibraltar,

the number of deaths, and the proportion per cent. of the deaths to the mean strength, from the 21st December 1814, till the 31st December 1831. Mean strength. Deaths.

Ratio per cent.

of deaths.
1815, | 4000

39
1816,
4000

33
1817,
4000

2.2
1818,

4000
3523

1.2
1820,

3139 1821,

2943 1822,

2802 1823,

2809 1824,

3201 1825,

3547 1826,

3627 1827, 3396

32 18:28,

3309

444 1829,

3837 1830,

3785 1831,

3627

Mean of 17 years, 3267 66

During the eight years which preceded the 20th December 1822, the annual ratio of mortality in the garrison of Gibraltar was 1.1 per cent. and the ratio of men invalided 3.3 per cent.'

Return of the mean annual strength of the garrison of Malta,

the number of deaths, and the ratio per cent. of the deaths from the year 1824 till the year 1831 inclusive.

Average strength. Deaths. Ratio per cent. 1824, 1928

54

2.8
1825,
2036

21
1826, 2610
1827, 1776
1828,

2667

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3.4

1822,

86

Return of the mean annual strength of the troops employed in

the Ionian Islands, the number of deaths, and the proportion per cent. of the deaths from the year 1820 till the year 1832 inclusive. Mean strength.

Deaths. Ratio per cent. of deaths. 1820, 2704

59

2.2
1821,
3139

119
3139
1823, 3840

111
3517

101
1825, 3358
1826, 3375
1827, 3439

94
1828, 4056

147
4056
138

3.4
1830,
4394
118

2.7
1831, 3340

50 1832, 3244

1824,

69

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67

1829,

1.5

46

1.4

2.6

Mean of 13 2162 years,

General abstract of the preceding Returns.

Stations
ē and corps.

No. years in.
xoo cluded in the

"returns.

Mean annu-
al strength.

Mean ratio
7 of sick per
GT Mean an.

number of

Mean an. ra-
6. deaths.
Gtio of deaths

per cent.
Mean an. ra.
tio of men in-
cent.
val. per cent.
Tot. an. loss
by death and
invaliding.

901

Ireland, 32 36921 5.1 576
Madras,

2 8717 12.4 713 8.1 Royal Regt. 24 1067

92 7.6 2.3 10. 59th Regt.

69 7.8 3.1 10.8 Gibraltar,

3267

66 2. Malta, 8 2226

34 1.5 Ionian Islands, 13 3467

93 2.6 Were comprehensive returns of the different divisions of the British army published, and precise results deduced from them similar to the preceding tables for a period of twenty or thirty

years, we should thereby be able to appreciate the influence of the climate of particular stations upon the health of troops, and to anticipate to a certain degree the mean ratio of sick, the mean ratio of invalids, and the mean ratio of deaths that would occur among any number of troops which might be employed in each station or colony. The advantages which might result from an intimate knowledge of these facts are so obvious, both for political and scientific purposes, that it would be considered a work of supererogation were I to attempt to enumerate them.

Art. V.- Observations on the Character and Treatment of

Iritis, with Preliminary Remarks on the Anatomical Structure and Physiology of the Iris, necessary to the elucidation of the Phenomena it presents during Inflammation, and certain Pathological Conditions that result. By CHARLES WARBURTON RIGG3, Esq. Surgeon. I HE ordinary diameter of the iris is about a line, its direction vertical, and its shade of colour presenting endless variety. On its anterior surface are observed two concentric circles, differing in depth of tint in different individuals; the greater ring, or that near the ciliary circumference of the iris, is broader but of lighter colour than that near the pupillary margin. Striated lines are discernible passing towards the pupil, as they approach it they interweave. In some cases its anterior aspect presents a mottled or marbled appearance, from the colouring matter being distributed in points. Whatever its colour is when closely examined it will be found rich and velvety. The necessity of the utmost familiarity with its appearance will be hereafter insisted on. The substance of the iris is described by some anatomists as composed of two laminæ, separable near the greater circumference, but intimately blended towards the pupil, converging and uniting into a membranous zone. Professor Maunoir of Geneva, by means of a powerful lens, distin. guished muscular fibres in the iris, which he described as forming two kinds of planes ; an external, radiated, broader, and corresponding to the outer coloured ring, dilating the pupil; an inner one, narrower, with concentric fibres, acting as a sphinc. ter. The existence of the membrane of the aqueous humour, which, if present, must cover the front of the iris, is doubtful. The reasoning in support of the non-existence of this membrane is drawn chiefly from the secretion being formed principally in

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the posterior chamber. The capacity of the anterior exceeds that of the posterior chamber ; the former is computed at the depth of a line and half, the latter at one-fourth of a line ; according to Mr Guthrie the greater part of the fluid passes from the posterior to the anterior chamber.*

Of the three sets of arterial branches going to the iris, those derived from the muscular arteries, the anterior ciliary, require most attention, as increased vascularity of them affords one cha. racteristic diagnostic mark of iritis, at least in an acute form. They pierce the sclerotica within about two lines of the cornea after running from its posterior aspect, between that tunic and the conjunctiva, and after passing through the ciliary ligament, they anastomose with the long and short ciliary filaments.

The nerves distributed to the iris proceed chiefly from the lentieular ganglion, a few twigs arising from the nasal. Notwithstanding the statements of some anatomists, it is, I believe, generally admitted, that the proof of the muscularity of the iris is established by analogy rather than actual demonstration of muscular fibres. The analogical evidence that goes to confirm the opinion of its muscularity it were tedious to enumerate. One phy. siological fact, which strongly associates the laws that govern the action of the iris with the muscular system, is its contraction from galvanism. Dr Jacob inserted a needle in the iris of a malefactor, which was excited to brisk action by the galvanic aura. This experiment was performed at the College of Surgeons in Dublin, in 1828. Those natural causes that actuate and modify the motions of the iris fall more immediately to be noticed. A voluntary power over the iris must be admitted. Cases well authenticated have been adduced. Dr Roget's account of the voluntary power he is capable of exercising over the motions of his irides must establish it. f I heard a teacher of anatomy relate the instance of a young gentleman who could at pleasure obscure the view of a near object, while the visual application was continued unchanged, without alteration or motion in the globe; this was effected by a dilatation of which the individual was unconscious, but very appreciable to an observer. This fact tends to invalidate Mr Travers's hypothesis of the motions of dilatation being dependent on elasticity. It seems more accordant with a just consideration of the action of dilatation to suppose that it is vital, and produced by radial fibres, whose stimulus is the state of tension into which the antecedent contraction has thrown them.

The causes, then, that may be stated as influencing its

• Lectures on the Operative Surgery of the Eye, p. 450. + Vide, Travers's Synopsis.

contractions are, 1st, volition, 2dly, the stimulus of light, 3dly, the sympathy with the retina, 4thly, concert with its fellow. The second cause assigned, that from the direct stimulus of light, independently of the retina, is founded on the observance of the power remaining in complete amaurosis; whilst in morbid dilatation, mydriasis, the sensibility of the re!ina continues unimpaired, the iris being almost immoveably dilated. I cannot adopt the opinion of Mr Travers, that sympathy of the iris and retina is ascribable to the connection of the ciliary nerves and retina ; and still less the conjecture, that apposition of the lenticular ganglion to the optic nerve, affects the union. Sympathies exist in other parts that cannot depend on a junction of nerves. In the present state of knowledge it is better to rest satisfied with the information afforded by the term contiguous sympathy, than to explain physiological phenomena by forced inferences.

Intiammation of the iris may be considered as simple or specific, as it comes on in a healthy state of the system, or arises during the existence of what are called specific or constitutional diseases. Another division, like that of inflammation in other parts, into acute, subacute, and chronic, must not be omitted. The epithet subucute conveys a more accurate idea of the slower forms of this affection. The term chronic denotes, in the general acceptation, the condition that remains after the subsi. dence of active inflammation, or a slow and irregular species of inflammatory action. Cases of iritis are not frequent; yet forty years ago the disease had not been recognized, or at least no account of it published. A German author wrote the first treatise on it. In Mr Howard's work on the venereal disease, the affection is noticed, and designated venereal ophthalmin. · Notwithstanding the frequency of the disease, and the lengthened notice of it in modern systematic books on the eye, and the able treatise of Mr Lawrence on the subject, practitioners are not, it is feared, sufficiently acquainted with the disease, so as to discriminate the first indications of the affection, when the inflammation can, in almost every case, be arrested. Books on the subject are not accessible to the bulk of practitioners ; and my object in drawing up this article, has been to lay before the numerous readers of this Journal a brief treatise on iritis, containing the opinions of the most approved writers and teachers, with deductions from a pretty extensive opportunity of observing the affection, and of acquiring the collateral information that the subject naturally embraces.

I have known the physician to an extensive hospital overlook the seat of the inflammation, treating it with ordinary antiphlogistic measures, until the effective means were nearly unavail. ing. In private practice errors of this kind often occur; and I

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