If you obtain a copy of the couple?s marriage certificate, it should give you their townlands (addresses) at the time they married plus their fathers names and occupations. With that information it may be possible to locate the family homes.
You can view the certificates on-line on the GRONI website, using the ?search registrations? option:
https://geni.nidirect.gov.uk
(You will need to open an account and buy some credits. It costs ?2 to a view a certificate). I see the date of the marriage was 31.10.1878 and it was registered in Larne.
If you post the relevant information, I can search and see if I can trace the 2 families.
Tradition was to marry in the bride?s church (which should be on the certificate, unless it was a Registry Office marriage). That church may be the place to look for her baptism and that of any siblings. The records may not be on-line and you may need to get someone to go to PRONI (the public record office) in Belfast to look at the copies held there.
I can see a John Ogilby in Sheriff?s Land, Kilwaughter in 1861, in Griffiths Valuation. He had plot 6c which was a house and garden, such as a weaver or labourer would have had. However I can?t say at this stage whether that?s Samuel?s family without more information from the marriage certificate.
There were a couple of Ogilby families in Kilwaughter in the 1851 census (which is not complete). They could be connected to your family. One of them had evidently moved over from Scotland sometime after 1823:
http://www.census.nationalarchives.ie/pages/1851/Antrim/Upper_Glenarm/Kilwaughter/Drumnadonaghy/12/
(Most of the Presbyterian families in that area originated in Scotland but the main migration was in the 1600s).
You ask why your ancestors might have left Ireland. I am sure they left for the same reasons that 2 million others did. To find work. Ireland has very few natural resources (no oil, coal, iron ore etc) and so did not benefit from the industrial revolution in the 1800s, the way Scotland, England, the US, Canada & Australia did, which created hundreds of thousands of comparatively well-paid new jobs in new industries (coal mining, steel making, railways, ship building etc). So that was a big pull factor. There had also been a huge population explosion in Ireland going up from about 3 million people in 1750 to 8 million in 1830. There simply weren?t jobs for all those people. In much of Ireland the only employment was subsistence farming topped up in Ulster and one or two other areas with a bit of linen weaving. And then the straw that broke the camel?s back, along came the famine, numerous times throughout the 1800s. The worst period was when the potato crop failed almost completely 3 years in a row in the late 1840s, and then partially several more years after that.
Other factors led to the continued emigration too, eg early mechanisation on farms. With new machines to turn the soil and plant seed, farmers no longer needed an army of agricultural labourers to help on the farm. So those jobs were rapidly disappearing. Likewise mechanisation had led to linen factories being set up in places like Belfast. These made home weaving uneconomic and so also upset the labourer?s family economy. Agriculture was the biggest single employer in Ireland, but it was mostly a barter economy. Few people had any ready cash save what they could make from weaving or any government sponsored work such as building new roads. So when the opportunity arose to get jobs with a regular wage packet, as opposed to a few pence from your father each week, the decision to migrate wasn?t really all that hard to make. So it was as much about economic betterment as anything. The famine wreaked havoc in most of Ireland but in Co Antrim, a comparatively wealthy county, it wasn?t too severe (and most bigger farmers had not been one crop dependant) so I would say it was less of a reason for your particular ancestors leaving than it was for others elsewhere in Ireland.
There was a massive tide of migration all through that century, including long before the famine. Years after the worst of the famine it?s impact was still being felt across Ireland, and there were still plenty of much better job opportunities in Australia and the USA. (After Scotland and England, the USA was the most popular destination for emigrants with about 40 to 50% choosing it. Only about 5% of Irish emigrants chose Australia and New Zealand, possibly due to the costs and length of the voyage).
Dates of birth for the children appear to be:
Mary 21.5.1879
Ellen 18.11.1880
John 30.10.1882
Looking at the 1901 census I see quite a few Ogilby households in the Larne & Kilwaughter area. Many were Non Subscribing Presbyterians (sometimes also known as Unitarians). So if you decide to check church records to trace the families backwards make sure you check the NSP records as well as those for the Presbyterian Church in Ireland. (The records are in PRONI in Belfast).
I can see 3 Ogilby families in Larne in the current phone book but whether they are related or not is impossible to say at this stage:
http://www.192.com/people/search/