Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Warship | tons ( L.ton ) | Horse- power | Speed ( Knots ) | Main Artillery | Built Year |
| --- | --- | --- | --- | --- | --- |
| O'Higgins | 1,101 | 300.0 | 12.0 | 3x115-2x70-2x12-pounders | 1874.0 |
| Chacabuco | 1,101 | 300.0 | 11.0 | 1x115-2x70-2x12-pounders | 1874.0 |
| Abtao | 1,051 | 300.0 | 8.0 | 3x115-3x30-pounders | 1870.0 |
| Magallanes | 772 | 260.0 | 115.0 | 1x115-1x64-2x20-pounders | 1874.0 |
| Covadonga | 412 | 140.0 | 7.0 | 2x70-3x40-pounders | 1859.0 |
| Esmeralda | 854 | 200.0 | 8.0 | 16x32-2x12-pounders | 1855.0 |
| Unión | 1.150 | 320.0 | 13.0 | 12x68-1x9-pounders | 1864.0 |
Question:
What is the primary artillery for the  1,051 ships?
Answer:
3x115-3x30-pounders