The People of Gibraltar
1830 - Dr John Hennen - The Lowest Order of Portuguese

General Don, Solare and Glynn - Duguid, Levi and 'Santos'
Dr Fellows, Dr Nooth  and Dr Pym - Pilkington, Holroyd and Caballero


In 1821 Dr. John Hennen was appointed as head medical officer for the British possessions in the Mediterranean. After residing in Malta, and then later in Corfu for several years, he was transferred to Gibraltar where he became the Medical Superintendent to the Garrison. He died in 1828 after one of the last yellow fever epidemics to visit the Rock - but not before having written a series of reports which he sent to the Director-General of the Army Medical Department.

The book - Sketches of the Medical Topography of the Mediterranean  which was published posthumously in 1830 was put together from these reports by his son Dr. J. Hennen. The book includes comprehensive studies of Gibraltar, the Ionian Islands and Malta published in the aftermath of the major yellow fever epidemics which struck Gibraltar between 1804 and 1828.
 
The book has nearly 700 pages of which the first 133 refer to Gibraltar. Superficially the book is a lengthy medical report on hygienic conditions on the Rock prevailing at the time as well as the state of health of the Garrison and the local  people. The end result is a good description of Gibraltar as it was in the early nineteenth century.

Gibraltar
Having been quartered on this rock for a part of the years 1809 and 1810, and having resided here as principal medical officer since January, 1826, (not to mention eight or ten anterior visits,) I have frequently been enabled to compare the topographical accounts of others with nature, and to satisfy myself on the spot, of the relative degree of credit to be given to them . . .

The natural flow of the sea is interrupted at a few points by the projection of moles, breakwaters, and batteries. The first of these, counting from the north end of the works, and adjacent to the neutral ground, is the Old Mole, and that battery known by the name of the Devil's Tongue.

The smaller craft moor in a little bay sheltered by these erections, and the water is frequently so smooth within them, as literally to resemble a mill-pond. From the Devil's Tongue, which is itself a breakwater at nearly right angles with the Line Wall, another very extensive work of the same description extends in a parallel direction for between three and four hundred yards, towards the King's Bastion. 

 
Between the southern extremity of this breakwater and the King's Bastion, a small wharf, now no longer used, extends a few yards from the old zoca into the bay; it is composed of loose stones, and offers little impediment to the flow of the water. . . Beyond this is Ragged-staff Mole, which, in this point of view, is of still less consequence. The New Mole is the next in succession to the southward : it lies about one mile and a half from the Old Mole . . . 



New Mole  ( 1860s - George Washington Wilson )

This work runs out to the southward of the Dockyard ; the depth of water is such, that ships-of-war can lie within a few yards of it, secured from ordinary winds. Connected with the Dockyard is a sort of basin or wet dock, called the " Camber," in which smaller vessels lie in perfect security. The water in this is almost stagnant . . . receives a great part of the filth of the sewers at the south, and some years ago was notorious for affording an offensive effluvium

The immediate neighbourhood of the spots now enumerated, demands the particular attention of the Medical Topographer. At each of them, public sewers discharge themselves, and public necessaries are erected ; from these causes, as well as from the occasional admixture of marine exuviae, the effluvia which arise are frequently very offensive . . .

In summer, when the afternoon sun lies for so many hours on the western face of the mountain, this nuisance is occasionally felt with peculiar severity . . . The offensive matters thrown up on the beach from the numerous small craft which are crowded around the vicinity of the Old Mole, must tend to deteriorate the purity of the air in no small degree . . . When it is recollected, that the floating population of the Bay of Gibraltar may be estimated at 2000 souls the year round, the amount of animal and vegetable offal must obviously be considerable. 


Waterport - Population of the Bay estimated at 2000 ( 1890s Gibraltar Museum )

To the north and the south of the King's Bastion, several public sewers empty themselves, but not having been carried into the sea, or even to low water mark, a great proportion of their contents is left on the beach. It is only since the administration of Sir George Don that they have been carried as far as they are at present, but it is proposed to extend them . . . Wooden sheds are also projected from the Line Wall in this neighbourhood, and serve as necessaries

In Rosia Bay, the sea is frequently, during the summer season, as stagnant as in a mill-pond. . .  From the Line Wall, which runs along the rocks, two wooden necessaries, similar to those near the King's Bastion, project, and the soil is in like manner retained on the sandy beach. Two large sewers also empty themselves here. Exhalations of a very offensive nature arise from these sources . . . 



Rosia Road and Rosia Bay

The nearest running stream to Gibraltar, is at the distance of about three miles from the garrison, on the side of the Bay where a small rivulet, collected from different springs in the hills . . . There is a small plantation of oranges, pomegranates, sweet canes, figs, &c. on its banks, and hence it is called the 'Orange Grove.' Agues are common among the inhabitants of this and the neighbouring villages of Campo, &c.; and in 1809 I knew an instance of a delicate young female, resident of the garrison, contracting that disease on a pleasure-party to this spot.

Inundation
The foot of the glacis in front of North Bastion is washed by the water of that part of the bay near the Old Mole.  Along the edge of the beach there is erected a causeway leading out to the Neutral Ground ; bounded by this causeway on the west, and by a part of the Rock and Spain on the east and south, there is an artificial inundation . . formerly a morass.

In plans of the fortress and of the siege of 1704, this morass is represented as communicating with the sea by a long narrow -channel running parallel with the beach for some distance. In 1732 it was dug two feet below the level of low-water mark in the bay.



 Map of Gibraltar  (  1704 - Col D'Harcourt )

To heighten all, there formerly existed a line of necessaries in the 'Orillon Ditch,' or Lazaretto, which, previous to 1814, discharged their soil into the inundation, and emitted a most offensive odour. . . .  they are now removed.

Mr. Amiel, in his answers to queries proposed by my predecessor relative to the epidemic of 1814, asserts, from his own experience, that several foreign recruits, who were successively employed at the pumps in the neighbourhood, had been attacked with fever of a bad type. . .

The cleanliness of this piece of water has been attended to much more strictly of late years than formerly. The commanding engineer, Major-General Pilkington, informs me, that on his arrival in the Garrison in 1819, the stench was almost intolerable, and so diffusive that it was experienced in his own quarters, in the very centre of the town, at the distance of several hundred yards. To this putrid exhalation he attributes the prevalence of fever in the Moorish Castle during the period of the epidemic

Ditches
The principal ditches  . . are those of Landport and Southport  . .  the former is a dry ditch . . . Southport Ditch is also a dry one and is divided into two . . . by an elevated causeway leading to the gate. It contains an old burial-ground which abounds in fig trees, on one side of the gate, and a kitchen-garden on the other.

  

South Port Gate and Ditch ( 1860s - George Washington Wilson )

The Aquaduct
The aqueduct is a very noble work, originally planned by the Moors. The present structure was commenced in the year 1571, after the plan of a Spanish Jesuit, and was finished in 1694. This aqueduct begins in the south, in the neighbourhood of the old burying-ground, and terminates in the centre of the town.

The water with which it is supplied, filters through the red sands (hereafter to be described), and runs through openings, technically called weep-holes, made of brick, into a reservoir, from whence, after rising to the height of eighteen inches, it is conveyed in earthen pipes to various parts of the town.

In itself, the aqueduct cannot be considered as any direct source of disease ; but the history of it, as well as of the tanks, is intimately connected with the estimate of sources of aqueous exhalations. The autumnal and winter rains are the grand means by which the aqueduct is immediately fed ; but there can be little doubt that water is supplied to it by the slower process of infiltration from the body of the mountain . .

Water Tanks 

The most extensive tanks are those for the use of the navy, in the immediate neighbourhood of Rosia Bay. . . Laborde . . . absurdly states that the water of the naval tanks is  'purified in coppers erected for the purpose.' The water flows into them without any preparation whatever ; it flows, as it does into all the other tanks, from the roofs of the houses, and the only means of purification consist in throwing in a few live eels, which eat up the animalculi, and occasionally they grow to such a size as to render them very desirable objects to be themselves eaten.

Among the public tanks there are some which are objects of curiosity to the antiquarian, especially one on Europa Flats, called the Nun's Well, supposed to have been formerly a Moorish bath; and one at the old Moorish castle.
 


Nun's Well ( Modern Photograph - Toromedia )

Arengo's, 
Boyd's and Cavallero's Buildings 
About midway between the castle and southern boundary of the town, (known by the name of Charles the Fifth's Wall,) is an insulated strip of the hill, with a gentle swell on either side ; it is inclosed with a stone wall, which renders it somewhat pyramidal to the eye : the base is occupied by a range of houses known under the name of "Arengo's Buildings," the upper part, by the Gardens called after the proprietor.

On each side a gully runs down. These gullies completely insulate the interjacent space, and give it a striking appearance from the Line Wall and Bay ; like the former, they discharge their winter-torrents through a crowded district of the town. Immediately to the southward is the fourth, or " Old Lime-Kiln  Gully," the water of which discharges itself, as the others do, through a crowded district. . . .

There are but few houses in their immediate neighbourhood where they take their rise on the side of the hill, but it is well worthy of remark, that they run their course in the direction of the Blue Barracks, City-Mill-Lane, Boyd's Buildings, Cavallero's Buildings, and other spots which were notoriously unhealthy during the epidemic years of 1804, 1810, 1813, and 1814. . .

. . . Cavallero's-buildings, situated close to Arengo''s gully ', they lie about the highest of any houses on the rock, but are now in a very different state from what they were in 1814. At that period, Cavallero's rivalled Boyd's for filth ; there were neither drains nor necessaries, and the inhabitants consisted of nearly 300 of the lowest order of Portuguese

Neutral Ground
Antiquarians assert that this isthmus, which in many points is of the nature of a quick-sand, was formerly covered by the sea, and that Gibraltar was an island, and the present Devil's Tower an ancient light-house in the channel between it and the main land.  


Devil's Tower ( Early 20th century photo )

However this may have been, it is certain, that in winter the sea has occasionally washed over nearly two-thirds of the isthmus when strong easterly winds prevailed, and with spring tides especially ; and hence, extensive pools have on these occasions been left behind, close up to the very gardens, of which there are a considerable extent on that part nearest to the garrison. . . during a very heavy swell of unusual duration . . . a breach of a few yards in extent was made behind the butchery. . . .

In a tenement belonging to a person of the name of Solare, there are three wells in a yard of the small dimensions of nine paces by four - In the centre one of these, the water is excellent, in the others it is much inferior and nearly brackish. . . . Besides the wells attached to private houses . . . there are six ponds and five Noria Wells . . . where the water is raised by some species of machinery, either a wheel turned by an ass, or a bucket and long lever worked by hand . . . .
 


Noria

On the neutral ground, are several extensive gardens, the Governor's Meadow, and the Garrison exercising-ground, the whole of which are formed of an artificial soil, which lies over, or is incorporated with the native sand. This made ground consists of the richest part of the mould dug out of the foundations of houses in the town, stable dung, the offal of the markets, houses, &c. which altogether form a compost of a very rich, highly fertile nature. 


North Front gardens in the Neutral Ground (1860s - Alexander Fisher )

Town Gardens
In looking over the town, the principal gardens which we observe, are those of his Excellency the Governor, which lie on nearly a dead level along the line wall, in the neighbourhood of Southport-gate ; near them, on the same level, is a small garden attached to the old bomb house : about the centre of the town is one, attached to the quarter of the Chief Engineer . . .

Close to it, another belonging to Mr. Glynn, an inhabitant, which stretches the line of vegetation  close to the Moorish Castle ; lower down, between the Commercial Square and the Civil Hospital, there is also an extensive garden, the property of Mr. Duguid, ( see LINK ) another inhabitant; and near it the garden of the Commandant of Artillery.

In the more southerly part of the town, at the mouth of a cul de sac formed on the side of the hill, in the neighbourhood of the old lime-kiln gully, is a piece of garden ground attached to the Garrison Library. Higher up, along the face of the hill, are 'Arengo's' gardens (between the two gullies already mentioned) and Levi's gardens, which lie on a piece of ground similarly circumstanced with Arengo's, having a gully on each side.

About midway up the hill, are certain enclosures called Farms,  all of which are within Charles the Fifth's Wall, and situated directly above the town ; they contain about ten acres, and, although interspersed with rocks, they produce vegetables of all kinds throughout the year: among these the profusion of artichokes is remarkable. 



 Contemporary map showing farms. The H shaped building on the middle left is Arengo's Garden ( 1830's - Piaget et Lailavoix - detail )

Southern Gardens
The most extensive garden grounds in the garrison lie to the southward of Charles the Fifth's Wall. Immediately on passing southport-gate, there is a small but rich garden in the ditch : advancing southward, we find the New Alameda, a very beautiful public promenade, constructed on the Red Sands, by his Excellency Sir George Don ; these are bounded on each side by roads, planted with rows of luxurious poplars and other trees, and abound in geraniums and flowering shrubs  . . .
 

. . . but by far the richest and most cultivated portion of the rock lies along the lower face of the hill, extending southward from the New Alameda to the Naval Hospital and Buena Vista. The most extensive and most highly cultivated grounds in this tract, are those belonging to the Commissioner and other Officers of the Naval Department.  


Mount Pleasant - or 'The Mount' -  home of the Naval Commissioner ( Early 19th century - Unknown )

There are also a considerable number of gardens attached to private houses, and several kept by market gardeners. These cultivated spots are not, as in the town, dispersed over, and dotting the surface; they form a kind of belt along the hill, which presents a striking and beautiful feature in the landscape, when viewed from the bay.

From the nature of the soil, the richness of the manure, and the industry of the cultivators in watering and manuring, aided by the warmth of the climate, the vegetation, especially of the gardens, is most luxuriant . .

Unhealthy Situations
Before entering into particulars, I may be permitted to make a remark upon one general source of alleged insalubrity. The refuse of vegetables in the markets and dwellings have been spoken of; and some merriment has been afforded to the critics while calculating on the imaginary connexion between cabbage stalks and contagion. . . .

The eastern side of the neutral ground has been observed to be more productive of disease than the western, and especially that portion of it in the vicinity of the  'Devil's Tower'. The diseases of the highest importance which have been remarked among the inhabitants, are remittent and intermittent fevers, dysenteric affections, and infantile marasmus. . .

At Catalan Bay there is a small detachment, which formerly remained for some months, but is now relieved every fortnight. The men who compose it are accommodated in barracks, and have in general enjoyed excellent health, though on the eastern beach they are in a situation quite distinct and insulated from the neutral ground.
 


  
Barracks in Catalan Bay ( Mid 19th Century )

Boyd's Building and Library Gardens
Within the town there formerly existed several spots remarkable for their filth, and for the crowded state of the inhabitants. Many of these places have been entirely new modelled ; the low ill-ventilated sheds, which encumbered the surface of the ground, have been removed ; premises of a more permanent nature have been repaired, and greatly improved, and, in several instances, the whole of the former buildings have been razed, and edifices of a very superior character have been erected, insomuch, that persons who were familiar with Gibraltar before the epidemic of 1814 can now scarcely recognise many parts of it. Among the best known of these situations is the extensive plot of ground formerly occupied by "Boyd's Buildings."

These buildings have been pulled down, and a very handsome pile has been constructed on the spot. This pile was only finished in 1825. . . . In the Chronicle and Commercial Intelligencer, the notices for the sale . . .appeared in 1823 . . . I will venture to assert, that so many thousand feet of crowded and filthy habitations, could not be found in any other garrison on the face of the globe.

This spot is remarkable as being the point where the epidemic of 1804 first made its appearance. 'Santos,' who is reported by Sir James Fellows and Dr. Pym to have been the original importer of the fever, lived in a part of those buildings ; and the Spanish smugglers, upon whom the suspicion of importation also fell, lived, and one of them was buried in the Library Garden, which is only separated from Boyd's Buildings by a narrow lane . . . The Library Garden was never a very clean neighbourhood, and even now it requires strict attention from the police, the back part especially.

Dr. Nooth . . .  considered that a large lime-kiln in this neighbourhood was, to use his own expression, 'part and part in the general mischief.'This kiln is built at the upper part of a gully, at the embouchure of which Boyd's Buildings are situated.

Marriages, Births and Deaths
There are no very accurate accounts of marriages, births, and deaths for the period preceding the epidemic of 1813 to be procured. The population of Gibraltar has at all times been a fluctuating one . . . It is extremely difficult, if not impracticable, to obtain regular returns, even of deaths : they are made separately, by each of the three religious persuasions that compose the community; and sometimes the necessary data on which to found these documents are wanting. Thus the mortality in the great epidemic season of 1813 has never been accurately stated. . .

Food
 . . The plants of Gibraltar are liable to blight and to the depredations of insects, as in all other countries ; but it is not probable that the public health has ever been influenced by these occurrences : it is only in districts where large quantities of grain and other provision for human food are raised, that such consequences are directly experienced.

In an indirect mode, however, the public health of Gibraltar may, and I believe has suffered from grain and vegetables which have undergone morbid changes. Potatoes are frequently kept in large masses ; they heat, ferment and putrefy, and in this state are often brought to market.

Unsound or damaged grain and flour are also often met with ; they are never used by the troops or more respectable classes; the lower orders, doubtless, occasionally employ them, but they are still more frequently purchased for the purpose of exportation, especially to Barbary, whenever a scarcity takes place in that country. Considerable quantities of damaged grain and unsound potatoes were sent from Gibraltar to Tangier in the spring of the year 1826, through the commercial operations of the Jews.

I am not aware of any practices in domestic or popular medicine peculiar to Gibraltar : the various classes of inhabitants adopt those to which, by national habits, they are accustomed. Of the Civil Hospital I have already spoken : the practice there is conducted on the principles of the British schools. Examinations are ordered to be held of all foreign practitioners, who receive a license under the sanction of this examination, and the, recommendation of the principal medical officer.

The police regulations guard, in a certain degree, against the evils attendant on the employment of empyrics and interlopers. On the last investigation on this subject, a labourer and a blacksmith were among the list of practitioners of physic and surgery. Gibraltar is not particularly remarkable for the longevity of its inhabitants, although an ordinary proportion of old people are to be met with.


Holroyd
In the convent chapel, there is an inscription commemorative of an English merchant named Holroyd, ( see LINK ) who died in the year 1758, aged ninety-six, after a residence of fifty-three years and six months in the garrison; and a man, a native of the rock, died in the Civil  Hospital in 1826, in his one hundred and first year.

While I write, an old woman, said to be one hundred and five years of age, lives in the garrison. I was called to see her, as affording an instance of senile dentition. I doubt this being a fact; but that she is beyond an hundred, appears to be clearly established.

Sir John Galt

Almost all travellers and voyagers in the Mediterranean mention it incidentally, though some of them, as Laborde and Galt, ( see LINK ) afford very inadequate and erroneous descriptions . . .

Garrison, Exchange and Commercial and Medical Libraries
The Garrison Library is a noble institution, originally commenced in the year 1793, by the officers then quartered on the rock. . . There is also a library founded by the merchants, which contains several good books, and excellent accommodation to study them. . . The Medical Department Library is of recent origin, and is far from contemptible; its catalogue comprises upwards of 500 volumes. . . I am not aware that Gibraltar has gi
ven birth to any individuals pre-eminent in medicine, surgery, or the collateral sciences.

Barracks
 
The barracks occupied by the soldiers, in this fortress, have been progressively improving for several years. Those at present tenanted are of two classes, casemates and detached buildings. To the first belong the new casemates at Landport, and those at Orange Bastion, and at the King's Bastion. To the second, the Moorish Castle, Gunners' Barracks, Town range and Hargrave's parade within the town ; and South barracks, Rosia, Windmill Hill, and Europa in the southern district ; to these may be added a few detached wooden buildings about Buena Vista, occupied principally by married people, and other outliers.  


Casemates Barracks  ( 1860s - George Washington Wilson )

Hargrave's Parade Barrack is occupied by the Sappers and Miners ; it is a stone building of two stories high, in the vicinity of the Southport Ditch.



 Hargrave's Parade ( Unknown )

Town Range Barracks are the largest and the best within the town ; they lie to the southward of the last mentioned, at forty-five feet above the level of the sea, and out of the line of direction of the lime-kiln gully. They are of two stories, built of stone, and form one side of a level street, parallel to the main street.   


Town Range Barracks ( Mid 20th century )

The South Barracks are a conspicuous range of stone buildings of three stories, situated on a plateau of the southern division of the rock. 



South Barracks ( 1860s - George Washington Wilson ) 

Rosia Barracks were formerly stores for the Commissariat, and were fitted up in 1817 for a West India regiment, which suffered much in this garrison from pneumonia
  

Rosia Barracks ( 1860s - George Washington Wilson )

Windmill Hill Barracks consist of two buildings, some hundred yards distance from each other, on a long range of two stories built of stone, situated under the southern pinnacle of the rock, and having a southern aspect. 


Windmill Hill Barracks ( 1850s - Francis Frith )

The Gunners' Barracks consist of a house of two stories, built of stone; it is occupied by the Royal Artillery, and is celebrated in the annals of Gibraltar epidemics, as a spot where fever raged in 1804.

 The Brewery Barracks are the most southerly on the rock : they are occupied by the Ordnance, and consist of a mass of stone buildings of one story ; they are dry and airy, but cold in the winter months. These barracks lie on the eastern side of that part of the rock called Europa Flats, 110 feet above the level of the sea. The roads laid out on these flats, by Sir George Don, have rendered them of very easy access, and the cool breezes which constantly perflate them, together with the expansive prospect, have rendered Europa quite the summer promenade. 


The Brewery Barracks ( 1860s - George Washington Wilson )

Mode of Living of the Troops
The ration of the soldiers has been considerably improved in Gibraltar of late years; the fresh meat is of better quality, a change effected by the system of stall-feeding the contractor's cattle.

The salt rations are also of superior quality, not only because the supplies are more frequent, but that proper storage is now found for them. The state of peace with Spain must obviously affect the supplies in general of the Garrison of Gibraltar ; and the particular state of the cattle must depend, in no small degree, on the abundance of food procured for them from that country.

The bread, served to the troops, is baked in the garrison, at the Commissariat Bakehouse, and is of excellent quality. The wine is sound and good ; but the soldiers rarely confine themselves to its use. The facility of procuring wine and spirits too often tempts to the abuse of these liquors, especially among the men employed in the King's Works, who are paid extra for their labour ( see LINK )

 . . .The water is still continued to be carried on donkeys, in small barrels, to the barracks and hospitals ; a mode which, perhaps, from the elevated site of several of these buildings, can never fully be obviated, until tanks are erected in their neighbourhoods. . . . The times of parade and exercise, as well as the dress of the troops, are regulated by the season. The troops are exercised, principally, on the Neutral Ground.
 


Parade at Neutral Ground   ( 1897 - Gibraltar Museum )

Corporal punishment is universally on the decline : many less severe and equally effectual substitutes are now employed; but I apprehend that it would be worthy of consideration, whether some of our military punishments might not be made more subservient to the public good.

Might not the knapsack drill, for instance, be replaced by some fatigue duty within the barracks, and two or three hours, which are thus absolutely wasted, be employed in promoting the cleanliness or comfort of the better sort of soldiers ? 


One would have expected that any account written by a scientist - and a compilation of a medical superintendent's  reports to his superiors certainly qualifies as such - would have been a relatively dispassionate affair. After all the only axes Dr. Jennin could possibly have had to grind were his opinions on what had caused the yellow fever epidemics on the Rock and how to avoid them in the future.

The fact that one needed to have an answer to the first in order to be able to do so for the second was not lost to Dr. Hennen.  Unfortunately in 1830 nobody had yet made a connection between monkeys, cross species transmission and the virus-carrying vector mosquito Aedes aegypti ( see LINK )

The 'great' debate after the 1828 epidemic was between the contagionists, who believed the disease was transmitted from person to person by contact, and the anti-contagionists who thought that all diseases were caused by environmental factors such as infectious airs or miasmas.

Although Hennen seems to hover between one theory and another, his constant references to the filthy and smelly conditions found on the Rock would place him on the anti-contagion side. Whatever the case the general prejudices are clear - the dirt is entirely non-British.

It is the lack of any sense of hygiene among the locals that leads to the infectious airs that cause the disease. And should this theory happen to fall, then it is their careless and over-crowded style of living and their lack of any sense of cleanliness,  that increases contact and spreads contagion.

Perhaps a small detail but it is perhaps symptomatic of British attitudes towards local residents at the time that Hennen fails to name the long-lived local non-British man and woman but does so for Holroyd - a British born merchant. He was by no means alone in this kind of blind-spot as his comments echo those of Robert Montgomery Martin writing about the effects of yellow fever in Gibraltar in 1837 ( see LINK )

The distinction between the well run barracks and the awfulness of the town and its market place are well drawn and it is the British - via General Don's administration - that are credited with improving Gibraltar's inadequate sanitary infrastructure. No mention of the fact that these 'improvements'  were thoroughly inadequate - other than Hennen's giveaway remarks on all those smelly outlets into inappropriate places on to the Bay.

Don's sewers didn't work.  This is what the historian  Lawrence A. Sawchuck, had to say about them;

Unfortunately the system was poorly designed; despite the natural incline of the town, the plan did not allow for sufficient flow to keep the waste matter moving out to the Bay. No system of sewer flushing had been planned and attempts to retrofit the system with pumps to flush with salt water, failed. The entire system had the effect of bringing waste from the upper portion of the town to the lower . . . and depositing it there, underneath the main thoroughfares.

When, finally, the hard winter rains dislodged the waste and forced it into the bay, the shortness of the mouths of the drains ensured that the effluvia was deposited above the low water mark, causing the seafront to be continually bathed with noxious organic matter.

 
All of which of course, was what Hennen found and described so fully. Unfortunately his perspective throughout was one in which - to use a double clich√© - the British administration came out smelling of well-meaning but hard-pressed roses while the locals continued to stink to high heaven.  Gibraltar was a fortress - the locals were there on sufference.