In the last 10 days there has been a glimpse of the scale of the heroin trade in Dublin. Twentytwo kilograms of heroin hidden in the door panels of three cars, and almost four kilos packed into a single rucksack, are in the hands of the Garda National Drug Unit, rather than those of the criminals.
Both hauls were believed to be destined for west Dublin, where dealers would have cut the drug, adding soluble powder - probably fructose or lactose - to bulk it out.
Then the brown mixture would have been bagged into between 400,000 and 750,000 street deals, depending on the purity.
Neither gardai nor community workers believe that Dublin's heroin supply will dry up as a result of the seizures. There has been no immediate effect on the price of a street deal throughout the city, which has been stable at £20 for the last two years. It is possible that a stockpile of heroin has prevented a shortage, but more likely that other dealers have stepped in by shipping smaller consignments to mop up the customers.
In the last year the price has dipped as low as £10 a deal for poorer-quality heroin, usually sold to first-time users who are smoking rather than injecting the drug. But the £20 note is still the most common note in a drug-dealer's stash of proceeds.
No one knows how much heroin Dublin's addicts consume because no one knows how many addicts there are.
The worst-case scenario of 10,000 addicts - a figure disputed by some experts - would mean the two recent seizures represent about a month's supply, as most addicts would use between three and four deals a day.
The 1996 figures, the latest available from the Health Research Board, showed there were almost 4,000 drug addicts presenting for treatment in the Eastern Health Board area.
New regulations in place since October 1st should mean that every addict being prescribed methadone is now registered. So far 3,290 addicts have registered under the new regulations.
Many people familiar with the drugs trade were surprised by the size of the two consignments seized in the past nine days - 22kg found in three cars which arrived on ferries from Britain to Dublin and Dun Laoghaire on Saturday, October 31st, and almost 4kg contained in a rucksack carried by a man in central Dublin last Thursday.
Unlike cannabis, which is shipped in bulk, heroin is associated with small-consignment runs by couriers, usually addicts themselves who are paid to carry the drugs, often internally.
In the whole of last year gardai seized just 8.2kg of heroin, a third of the total seized in the two recent hauls. Garda Drug Squad officers believe that if 20kg shipments were a weekly event the price of heroin would have dropped through the floor.
"What has happened in the past with large seizures is that whatever organisation is bringing in the drugs would tend to close down, at least temporarily, so they can tighten up the operation," a senior Garda source said.
Dublin's heroin is shipped through Manchester, London, and to a lesser extent Liverpool. "That was illustrated last year when a number of large seizures in London and the arrest of some Turks led to a number of shortages in Dublin, indicating to some extent how the business rests on a small number of people in London."
The impact of a large seizure is not catastrophic for a drugs gang if those arrested with the drugs are simply couriers.
While the "street" value is in the millions of pounds, the drugs may have cost the gang less than a tenth of that, and a seizure is a debt that has to be paid for from the profits of previous shipments.
Catching the main drug-dealer with a smaller amount, two or three ounces, can have a more devastating effect. Couriers are dispensable and the most powerful drug-dealers avoid contact with the source of their profits.
Things have improved in some of the worst heroin blackspots in the south inner city, with an increased Garda presence in the last six weeks.
The chairman of Rialto Network, Mr Tony Mac Carthaigh, believes the policing is having an effect in Fatima Mansions, dubbed a heroin supermarket by its residents earlier this year. "There has been an improved police presence in the last five to six weeks, with uniform gardai on the beat, wearing the yellow jackets, which makes them even more visible. My own feedback is that things have quietened down considerably. And long may it continue." Drug-dealing that was carried out openly now goes on "under cover of darkness".
In Inchicore, St Michael's Estate has also seen a large increase in gardai.
One resident says that six officers patrol the estate regularly. However, the layout of the complex makes it impossible to police every corner and dealers block the lifts when they are collecting money.
According to a north-side Garda drugs source, "realistically most of the dealers are people who are dealing for a local market. You have a guy taking the Ryanair flight over to Manchester or London with a girl and they bring back an ounce or two. It's handy enough."
When things get quiet it usually has to do with the presence of Garda uniforms in an area, rather than a shortage of heroin. They call it the "waterbed effect". Sit on the problem in one area or at one time, and it moves into another.
Office workers in the city-centre have noticed in the last month that a derelict building owned by a private developer off the quays is apparently being used for the first time as a centre for drug-dealing.